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Cosan S.A. – ‘20-F’ for 12/31/20 – ‘EX-101.DEF’

On:  Friday, 4/30/21, at 3:18pm ET   ·   For:  12/31/20   ·   Accession #:  1554855-21-173   ·   File #:  1-40155

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  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

 4/30/21  Cosan S.A.                        20-F       12/31/20  194:46M                                    IRIS Business Svcs/FA

Annual or Annual-Transition Report by a Foreign Non-Canadian Issuer   —   Form 20-F   —   SEA’34
Filing Table of Contents

Document/Exhibit                   Description                      Pages   Size 

 1: 20-F        Annual or Annual-Transition Report by a Foreign     HTML   3.83M 
                Non-Canadian Issuer                                              
 8: EX-1.1      Underwriting Agreement or Conflict Minerals Report  HTML    159K 
 9: EX-2.5      Plan of Acquisition, Reorganization, Arrangement,   HTML    202K 
                Liquidation or Succession                                        
10: EX-4.13     Instrument Defining the Rights of Security Holders  HTML     78K 
11: EX-4.14     Instrument Defining the Rights of Security Holders  HTML    115K 
12: EX-4.15     Instrument Defining the Rights of Security Holders  HTML    107K 
13: EX-4.16     Instrument Defining the Rights of Security Holders  HTML    426K 
14: EX-8.1      Opinion of Counsel re: Tax Matters                  HTML     70K 
18: EX-13.1     Annual or Quarterly Report to Security Holders      HTML     56K 
19: EX-13.2     Annual or Quarterly Report to Security Holders      HTML     56K 
15: EX-11.1     Statement re: the Computation of Earnings Per       HTML     64K 
                Share                                                            
16: EX-12.1     Statement re: the Computation of Ratios             HTML     59K 
17: EX-12.2     Statement re: the Computation of Ratios             HTML     59K 
20: R1          Cover Page                                          HTML     97K 
21: R2          Consolidated statement of financial position        HTML    214K 
22: R3          Consolidated statement of profit or loss and other  HTML    175K 
                comprehensive income                                             
23: R4          Consolidated statement of changes in equity         HTML    137K 
24: R5          Consolidated statement of cash flows                HTML    215K 
25: R6          Consolidated statement of cash flows                HTML     67K 
                (Parenthetical)                                                  
26: R7          Operations                                          HTML     58K 
27: R8          Development of the Company                          HTML     90K 
28: R9          Corporate reorganization                            HTML     62K 
29: R10         Statement of compliance                             HTML     59K 
30: R11         Accounting policies                                 HTML     77K 
31: R12         Segment information                                 HTML   1.02M 
32: R13         Financial assets and liabilities                    HTML    947K 
33: R14         Other tax receivables                               HTML     71K 
34: R15         Inventories                                         HTML     67K 
35: R16         Investments in associates                           HTML    586K 
36: R17         Investments in joint ventures                       HTML     88K 
37: R18         Property, plant and equipment, intangible assets,   HTML    471K 
                goodwill, right-of-use assets and contract assets                
38: R19         Commitments                                         HTML     59K 
39: R20         Concessions payable                                 HTML    109K 
40: R21         Sector financial asset and liability                HTML     83K 
41: R22         Other taxes payable                                 HTML     86K 
42: R23         Income tax and social contribution                  HTML    231K 
43: R24         Provision for legal proceedings and judicial        HTML    200K 
                deposits                                                         
44: R25         Shareholders' equity                                HTML    132K 
45: R26         Earnings per share                                  HTML     98K 
46: R27         Net sales                                           HTML    125K 
47: R28         Costs and expenses by nature                        HTML     88K 
48: R29         Other income (expenses), net                        HTML     86K 
49: R30         Finance results                                     HTML    111K 
50: R31         Post-employment benefits                            HTML    155K 
51: R32         Share-based payment                                 HTML    240K 
52: R33         Subsequent events                                   HTML     67K 
53: R34         Recent accounting developments adopted by the       HTML     65K 
                Company                                                          
54: R35         New standards and interpretations not yet           HTML     64K 
                effective                                                        
55: R36         Accounting policies (Policies)                      HTML     78K 
56: R37         Accounting policies (Tables)                        HTML     63K 
57: R38         Segment information (Tables)                        HTML   1.01M 
58: R39         Financial assets and liabilities (Tables)           HTML    925K 
59: R40         Other tax receivables (Tables)                      HTML     69K 
60: R41         Inventories (Tables)                                HTML     65K 
61: R42         Investments in associates (Tables)                  HTML    574K 
62: R43         Investments in joint ventures (Tables)              HTML     85K 
63: R44         Property, plant and equipment, intangible assets,   HTML    449K 
                goodwill, right-of-use assets and contract assets                
                (Tables)                                                         
64: R45         Concessions payable (Tables)                        HTML    104K 
65: R46         Sector financial asset and liability (Tables)       HTML     78K 
66: R47         Other taxes payable (Tables)                        HTML     87K 
67: R48         Income tax and social contribution (Tables)         HTML    226K 
68: R49         Provision for legal proceedings and judicial        HTML    168K 
                deposits (Tables)                                                
69: R50         Shareholders' equity (Tables)                       HTML    129K 
70: R51         Earnings per share (Tables)                         HTML     87K 
71: R52         Net sales (Tables)                                  HTML    100K 
72: R53         Costs and expenses by nature (Tables)               HTML     86K 
73: R54         Other income (Expenses), Net (Tables)               HTML     85K 
74: R55         Finance results (Tables)                            HTML    105K 
75: R56         Post-employment benefits (Tables)                   HTML    150K 
76: R57         Share-based payment (Tables)                        HTML    236K 
77: R58         Operations - Additional Information (Detail)        HTML     64K 
78: R59         Development of the Company - Additional             HTML    238K 
                Information (Detail)                                             
79: R60         Corporate reorganization - Additional Information   HTML     63K 
                (Detail)                                                         
80: R61         Accounting policies - Schedule of Exchange Rates    HTML     63K 
                of Real for Functional Currencies of Subsidiaries                
                (Detail)                                                         
81: R62         Segment Information - Summary of Income or Loss     HTML    309K 
                (Detail)                                                         
82: R63         Segment Information - Summary of Financial          HTML    267K 
                Position (Detail)                                                
83: R64         Segment Information - Summary of Net Sales by       HTML    129K 
                Customer by Segment (Detail)                                     
84: R65         Segment Information - Summary of Information on     HTML     79K 
                Geographical Area (Detail)                                       
85: R66         Segment Information - Additional Information        HTML     63K 
                (Detail)                                                         
86: R67         Financial Instruments - Summary of Carrying Amount  HTML     83K 
                of Financial Assets (Detail)                                     
87: R68         Financial Instruments - Summary of Carrying Amount  HTML     92K 
                of Financial Liabilities (Detail)                                
88: R69         Financial Assets and Liabilities - Summary of Cash  HTML     64K 
                and Cash Equivalents (Detail)                                    
89: R70         Financial Assets and Liabilities - Summary of       HTML     72K 
                Financial Investments (Detail)                                   
90: R71         Financial Assets and Liabilities - Additional       HTML     82K 
                information (Detail)                                             
91: R72         Financial Assets and Liabilities - Summary of       HTML     65K 
                Marketable Securities (Detail)                                   
92: R73         Financial Assets and Liabilities - Summary of       HTML     62K 
                Restricted Cash (Detail)                                         
93: R74         Financial Assets and Liabilities - Summary of       HTML     74K 
                Trade Receivables (Detail)                                       
94: R75         Financial Assets and Liabilities - Summary of       HTML     59K 
                Trade Receivables (Parenthetical) (Detail)                       
95: R76         Financial Assets and Liabilities - Summary of       HTML     71K 
                Ageing of Trade Receivables (Detail)                             
96: R77         Financial Assets and Liabilities - Summary of       HTML     61K 
                Changes in Expected Credit Losses (Detail)                       
97: R78         Financial Assets and Liabilities - Summary of       HTML    103K 
                Receivables from and Payables to Related Parties                 
                (Detail)                                                         
98: R79         Financial Assets and Liabilities - Summary of       HTML     59K 
                Receivables from and Payables to Related Parties                 
                (Parenthetical) (Detail)                                         
99: R80         Financial Assets and Liabilities - Summary of       HTML     85K 
                Related Party Transactions (Detail)                              
100: R81         Financial Assets and Liabilities - Summary of       HTML     64K  
                Officers' and Directors' Compensation (Detail)                   
101: R82         Financial Assets and Liabilities - Summary of       HTML    373K  
                Loans, Borrowings and Debentures (Detail)                        
102: R83         Financial Assets and Liabilities - Summary of       HTML     75K  
                Non-current Borrowings (Detail)                                  
103: R84         Financial Assets and Liabilities - Summary of       HTML     66K  
                Carrying in Loans, Borrowings and Debentures                     
                (Detail)                                                         
104: R85         Financial Assets and Liabilities - Summary of       HTML     65K  
                Changes in Loans, Borrowings and Debentures                      
                (Detail)                                                         
105: R86         Financial Assets and Liabilities - Schedule         HTML     86K  
                Required to Comply Financial Covenants (Detail)                  
106: R87         Financial Assets and Liabilities - Loans,           HTML     75K  
                borrowings and debentures - Additional information               
                (Detail)                                                         
107: R88         Financial Assets and Liabilities - Summary of       HTML     73K  
                movement of leases (Detail)                                      
108: R89         Financial Assets and Liabilities - Summary of       HTML     64K  
                lease expense (Detail)                                           
109: R90         Financial Assets and Liabilities - Summary of       HTML     70K  
                Trade Payables (Detail)                                          
110: R91         Financial Assets and Liabilities - Summary of       HTML     61K  
                movement of the obligation with preferred                        
                shareholders (Detail)                                            
111: R92         Financial Assets and Liabilities - Summary of       HTML     87K  
                Derivative Financial Instruments (Detail)                        
112: R93         Financial Assets and Liabilities - Summary of       HTML    124K  
                foreign currency-related hedging instruments and                 
                interest rate swaps (Detail)                                     
113: R94         Financial Assets and Liabilities - Summary of       HTML     78K  
                Market Value of Senior Notes that are listed on                  
                Luxembourg Stock Exchange (Detail)                               
114: R95         Financial Assets and Liabilities - Summary of       HTML    128K  
                Carrying Amounts and Fair Value of Financial                     
                Assets and Financial Liabilities (Detail)                        
115: R96         Financial assets and liabilities - Summary of       HTML     85K  
                Financial Risks and Financial Performance (Detail)               
116: R97         Financial assets and liabilities - Summary of Net   HTML     81K  
                Exposure to Exchange Rate Variations on Assets and               
                Liabilities (Detail)                                             
117: R98         Financial assets and liabilities - Additional       HTML     68K  
                Information (Details)                                            
118: R99         Financial assets and liabilities - Summary of       HTML    123K  
                Sensitivity Analysis on Changes in Foreign                       
                Exchange Rates Impact on Profit Loss (Detail)                    
119: R100        Financial assets and liabilities - Summary of       HTML     81K  
                Sensitivity Analysis on Changes in Foreign                       
                Exchange Rates (Detail)                                          
120: R101        Financial assets and liabilities - Summary of       HTML    130K  
                Sensitivity Analysis on Interest Rates on Loans                  
                and Borrowings (Detail)                                          
121: R102        Financial assets and liabilities - Summary of       HTML    110K  
                Probable Scenario Considers Estimated Interest                   
                Rate (Detail)                                                    
122: R103        Financial risk management - Schedule of             HTML     64K  
                outstanding energy trading operations (Detail)                   
123: R104        Financial risk management - Schedule of             HTML     71K  
                outstanding energy trading operations (Details)                  
124: R105        Financial assets and liabilities - Summary of       HTML     77K  
                Credit Risk (Detail)                                             
125: R106        Financial assets and liabilities - Summary of       HTML     64K  
                Credit Risk Rating (Detail)                                      
126: R107        Financial assets and liabilities - Summary of       HTML    137K  
                Financial Liabilities (Detail)                                   
127: R108        Other Tax Receivables - Summary of Other Tax        HTML     76K  
                Receivables (Detail)                                             
128: R109        Other Tax Receivables - Additional Information      HTML     64K  
                (Detail)                                                         
129: R110        Inventories - Summary of inventories and written    HTML     68K  
                down of inventories (Detail)                                     
130: R111        Investments in Associates - Summary of Information  HTML    278K  
                in Associates of Company and Company's Ownership                 
                (Detail)                                                         
131: R112        Investments in Associates - Summary of Information  HTML     57K  
                in Associates of Company and Company's Ownership                 
                (Parenthetical) (Detail)                                         
132: R113        Investments in Associates - Summary of Financial    HTML     87K  
                Information of Associates (Detail)                               
133: R114        Investments in Associates - Summary of              HTML    157K  
                Non-controlling Interests in Subsidiaries (Detail)               
134: R115        Investments in Associates - Summary of Financial    HTML    105K  
                Position (Detail)                                                
135: R116        Investments in Associates - Summary of Profit or    HTML    113K  
                Loss and Other Comprehensive Income (Detail)                     
136: R117        Investments in Associates - Summary of Cash Flows   HTML     91K  
                (Detail)                                                         
137: R118        Investments in Associates - Acquisition of          HTML    139K  
                subsidiaries (Detail)                                            
138: R119        Investments in Joint Ventures - Summary of Changes  HTML     82K  
                to Investments in Joint Ventures (Detail)                        
139: R120        Investments in Joint Ventures - Additional          HTML     66K  
                Information (Detail)                                             
140: R121        Property, plant and equipment, intangible assets,   HTML     97K  
                goodwill, right-of-use assets and contract assets                
                - Additional Information (Detail)                                
141: R122        Property, plant and equipment, intangible assets,   HTML     60K  
                goodwill, right-of-use assets and contract assets                
                - Additional Information (Detail 1)                              
142: R123        Property, plant and equipment, intangible assets,   HTML     83K  
                goodwill, right-of-use assets and contract assets                
                - Summary of Depreciation on Straight-line Basis                 
                Over the Estimated Useful life of Assets (Detail)                
143: R124        Property, plant and equipment, intangible assets,   HTML    147K  
                goodwill, right-of-use assets and contract assets                
                - Schedule of Property Plant and Equipment                       
                (Detail)                                                         
144: R125        Property, plant and equipment, intangible assets,   HTML     59K  
                goodwill, right-of-use assets and contract assets                
                - Schedule of Property Plant and Equipment                       
                (Parenthetical) (Detail)                                         
145: R126        Property, plant and equipment, intangible assets,   HTML    140K  
                goodwill, right-of-use assets and contract assets                
                - Summary of Intangible Assets and Goodwill                      
                (Detail)                                                         
146: R127        Property, plant and equipment, intangible assets,   HTML     90K  
                goodwill, right-of-use assets and contract assets                
                - Summary of Intangible Assets (Excluding                        
                Goodwill) (Detail)                                               
147: R128        Property, plant and equipment, intangible assets,   HTML    126K  
                goodwill, right-of-use assets and contract assets                
                - Summary of transaction charts of right of use                  
                assets (Detail)                                                  
148: R129        Disclosure - Property, plant and equipment,         HTML     65K  
                intangible assets, goodwill, right-of-use assets                 
                and contract assets - Summary of transaction                     
                charts of contract asset (Detail)                                
149: R130        Commitments (Detail)                                HTML     81K  
150: R131        Concessions payable- Summary of Concessions         HTML     75K  
                Payable (Detail)                                                 
151: R132        Concessions payable - Additional Information        HTML     65K  
                (Detail)                                                         
152: R133        Concessions payable - Summary of judicial deposits  HTML     61K  
                (Detail)                                                         
153: R134        Concessions payable - Summary of leases and grants  HTML     91K  
                related to concession payable (Detail)                           
154: R135        Sector financial asset and liability - Summary of   HTML     81K  
                changes in net sector financial asset (Liability)                
                (Detail)                                                         
155: R136        Other Taxes Payable - Schedule of Other Taxes       HTML     79K  
                Payable (Detail)                                                 
156: R137        Other Taxes Payable - Summary of Amounts Due on     HTML     74K  
                Non-Current Liabilities and Maturity Schedule                    
                (Detail)                                                         
157: R138        Income Tax and Social Contribution - Additional     HTML     59K  
                Information (Detail)                                             
158: R139        Income Tax and Social Contribution - Schedule of    HTML     86K  
                Reconciliation of Income and Social Contribution                 
                Tax Expenses (Detail)                                            
159: R140        Income Tax and Social Contribution - Schedule of    HTML     57K  
                Reconciliation of Income and Social Contribution                 
                Tax Expenses (Parenthetical) (Detail)                            
160: R141        Income Tax and Social Contribution - Summary of     HTML    119K  
                Deferred Income Tax Assets and Liabilities                       
                (Detail)                                                         
161: R142        Income Tax and Social Contribution - Summary of     HTML    131K  
                Changes in Deferred Tax (Detail)                                 
162: R143        Provision for legal proceedings and judicial        HTML     68K  
                deposits - Summary of Provision for Legal                        
                Proceedings and Judicial Deposits (Detail)                       
163: R144        Provision for legal proceedings and judicial        HTML     81K  
                deposits - Summary Changes in Provision for Legal                
                Proceedings (Detail)                                             
164: R145        Provision for legal proceedings and judicial        HTML     82K  
                deposits - Summary of Principal Tax Proceedings                  
                for Which Risk of Loss is Probable (Detail)                      
165: R146        Provision for legal proceedings and judicial        HTML     93K  
                deposits - Additional Information (Detail)                       
166: R147        Provision for legal proceedings and judicial        HTML    111K  
                deposits - Summary of Principal Proceedings for                  
                Which Deem Risk of Loss as Possible (Detail)                     
167: R148        Provision for legal proceedings and judicial        HTML     64K  
                deposits - Contingent assets - Additional                        
                Information (Detail)                                             
168: R149        Shareholders Equity - Summary of Share Capital      HTML     78K  
                (Detail)                                                         
169: R150        Shareholders Equity - Additional Information        HTML     63K  
                (Detail)                                                         
170: R151        Shareholders' Equity - Summary of Other             HTML     89K  
                Comprehensive (Loss) Income (Detail)                             
171: R152        Earnings per Share - Summary of Calculation of      HTML     83K  
                Earnings per Share (Detail)                                      
172: R153        Net sales - Analysis of Revenue from Continuing     HTML     67K  
                Operations (Detail)                                              
173: R154        Net sales - Revenue Disaggregated by Products and   HTML     85K  
                Service Lines and Timing of Revenue Recognition                  
                (Detail)                                                         
174: R155        Costs and Expenses by Nature - Summary of Expenses  HTML     94K  
                by Nature/Purpose (Detail)                                       
175: R156        Other income (expenses), net - Summary of Details   HTML     81K  
                of Other income (Expenses), Net (Detail)                         
176: R157        Other income (expenses), net - Summary of Details   HTML     66K  
                of Other income (Expenses), Net (Parenthetical)                  
                (Detail)                                                         
177: R158        Finance Results - Summary of Finance Results        HTML    102K  
                (Detail)                                                         
178: R159        Post-employment Benefits - Summary of               HTML     66K  
                Post-employment Benefits (Detail)                                
179: R160        Post-employment Benefits - Additional Information   HTML     78K  
                (Detail)                                                         
180: R161        Post-employment Benefits - Summary of Defined       HTML     88K  
                Benefit Obligation and Fair Value of Plan Assets                 
                (Detail)                                                         
181: R162        Post-employment Benefits - Summary of Expense       HTML     61K  
                Recognized in Profit or Loss (Detail)                            
182: R163        Post-employment Benefits - Summary of Amount        HTML     69K  
                Recognised as Accumulated Other Comprehensive                    
                Income (Detail)                                                  
183: R164        Post-employment Benefits - Summary of Plan Assets   HTML     64K  
                (Detail)                                                         
184: R165        Post-employment Benefits - Summary of Assumptions   HTML     71K  
                to Determine Defined Benefit Obligations (Detail)                
185: R166        Post-employment Benefits - Summary of Changes in    HTML     66K  
                Discount Rate (Detail)                                           
186: R167        Post-employment Benefits - Summary of Changes in    HTML     59K  
                Discount Rate (Parenthetical) (Detail)                           
187: R168        Share-based Payment - Summary of Share-based        HTML    213K  
                Payment Arrangements (Detail)                                    
188: R169        Share-based Payment - Summary of Weighted Average   HTML     78K  
                Fair Value of Programs Granted and Principal                     
                Assumptions used in Applying Black-Scholes Model                 
                (Detail)                                                         
189: R170        Share-based Payment - Summary of Number and         HTML     65K  
                Weighted-average Exercise Prices of Share Options                
                (Detail)                                                         
190: R171        Share-based Payment - Summary of Share-based        HTML     58K  
                Compensation Expense (Detail)                                    
191: R172        Subsequent Events - Additional Information          HTML    109K  
                (Detail)                                                         
193: XML         IDEA XML File -- Filing Summary                      XML    375K  
192: EXCEL       IDEA Workbook of Financial Reports                  XLSX    358K  
 2: EX-101.INS  XBRL Instance -- csan-20201231                       XML  16.81M 
 5: EX-101.CAL  XBRL Calculations -- csan-20201231_cal               XML    571K 
 3: EX-101.DEF  XBRL Definitions -- csan-20201231_def                XML   3.97M 
 6: EX-101.LAB  XBRL Labels -- csan-20201231_lab                     XML   8.79M 
 4: EX-101.PRE  XBRL Presentations -- csan-20201231_pre              XML   4.83M 
 7: EX-101.SCH  XBRL Schema -- csan-20201231                         XSD   1.04M 
194: ZIP         XBRL Zipped Folder -- 0001554855-21-000173-xbrl      Zip   1.05M  


‘EX-101.DEF’   —   XBRL Definitions — csan-20201231_def


This Exhibit is an XBRL XML File.


                                                                                                                                                                                
<?xml version="1.0" standalone="yes" encoding="windows-1252"?>
<!-- Created by IRIS Business Services_Demo, Powered by IRIS Carbon -->
<link:linkbase xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xl="http://www.xbrl.org/2003/XLink" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
<link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
<link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
<link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
<link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
<link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
<link:roleRef roleURI="http://www.cosan.com/role/CoverPage" xlink:type="simple" xlink:href="csan-20201231.xsd#CoverPage"/>
<link:roleRef roleURI="http://www.cosan.com/role/ConsolidatedStatementOfChangesInEquity" xlink:type="simple" xlink:href="csan-20201231.xsd#ConsolidatedStatementOfChangesInEquity"/>
<link:roleRef roleURI="http://www.cosan.com/role/ConsolidatedStatementOfCashFlowsParenthetical" xlink:type="simple" xlink:href="csan-20201231.xsd#ConsolidatedStatementOfCashFlowsParenthetical"/>
<link:roleRef roleURI="http://www.cosan.com/role/ShareBasedPaymentTables" xlink:type="simple" xlink:href="csan-20201231.xsd#ShareBasedPaymentTables"/>
<link:roleRef roleURI="http://www.cosan.com/role/OperationsAdditionalInformationDetail" xlink:type="simple" xlink:href="csan-20201231.xsd#OperationsAdditionalInformationDetail"/>
<link:roleRef roleURI="http://www.cosan.com/role/FinancialriskmanagementScheduleofoutstandingenergytradingoperationsDetails" xlink:type="simple" xlink:href="csan-20201231.xsd#FinancialriskmanagementScheduleofoutstandingenergytradingoperationsDetails"/>
<link:roleRef roleURI="http://www.cosan.com/role/FinancialassetsandliabilitiesSummaryofCreditRiskDetail" xlink:type="simple" xlink:href="csan-20201231.xsd#FinancialassetsandliabilitiesSummaryofCreditRiskDetail"/>
<link:roleRef roleURI="http://www.cosan.com/role/AccountingPoliciesScheduleOfExchangeRatesOfRealForFunctionalCurrenciesOfSubsidiariesDetail" xlink:type="simple" xlink:href="csan-20201231.xsd#AccountingPoliciesScheduleOfExchangeRatesOfRealForFunctionalCurrenciesOfSubsidiariesDetail"/>
<link:roleRef roleURI="http://www.cosan.com/role/FinancialAssetsAndLiabilitiesSummaryOfMarketValueOfSeniorNotesThatAreListedOnLuxembourgStockExchangeDetail" xlink:type="simple" xlink:href="csan-20201231.xsd#FinancialAssetsAndLiabilitiesSummaryOfMarketValueOfSeniorNotesThatAreListedOnLuxembourgStockExchangeDetail"/>
<link:roleRef roleURI="http://www.cosan.com/role/FinancialriskmanagementScheduleofoutstandingenergytradingoperationsDetail" xlink:type="simple" xlink:href="csan-20201231.xsd#FinancialriskmanagementScheduleofoutstandingenergytradingoperationsDetail"/>
<link:roleRef roleURI="http://www.cosan.com/role/SegmentInformationSummaryOfIncomeOrLossDetail" xlink:type="simple" xlink:href="csan-20201231.xsd#SegmentInformationSummaryOfIncomeOrLossDetail"/>
<link:roleRef roleURI="http://www.cosan.com/role/SegmentInformationSummaryOfFinancialPositionDetail" xlink:type="simple" xlink:href="csan-20201231.xsd#SegmentInformationSummaryOfFinancialPositionDetail"/>
<link:roleRef roleURI="http://www.cosan.com/role/SegmentInformationSummaryofNetSalesbyCustomerbySegmentDetail" xlink:type="simple" xlink:href="csan-20201231.xsd#SegmentInformationSummaryofNetSalesbyCustomerbySegmentDetail"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EquityMember" xlink:to="ifrs-full_IssuedCapitalMember" xlink:title="Definition : ifrs-full_EquityMember to ifrs-full_IssuedCapitalMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EquityMember" xlink:to="ifrs-full_NoncontrollingInterestsMember" xlink:title="Definition : ifrs-full_EquityMember to ifrs-full_NoncontrollingInterestsMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EquityMember" xlink:to="ifrs-full_RetainedEarningsMember" xlink:title="Definition : ifrs-full_EquityMember to ifrs-full_RetainedEarningsMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EquityMember" xlink:label="ifrs-full_EquityMember_1" xlink:title="ifrs-full_EquityMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ComponentsOfEquityAxis" xlink:to="ifrs-full_EquityMember_1" xlink:title="Definition : ifrs-full_ComponentsOfEquityAxis to ifrs-full_EquityMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_StatementOfChangesInEquityTable" xlink:to="ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis" xlink:title="Definition : ifrs-full_StatementOfChangesInEquityTable to ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis" xlink:to="ifrs-full_RestatedMember" xlink:title="Definition : ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis to ifrs-full_RestatedMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RestatedMember" xlink:to="csan_IncreaseDecreaseDueToApplicationOfIFRS9Member" xlink:title="Definition : ifrs-full_RestatedMember to csan_IncreaseDecreaseDueToApplicationOfIFRS9Member" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PreviouslyStatedMember" xlink:label="ifrs-full_PreviouslyStatedMember" xlink:title="ifrs-full_PreviouslyStatedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RestatedMember" xlink:to="ifrs-full_PreviouslyStatedMember" xlink:title="Definition : ifrs-full_RestatedMember to ifrs-full_PreviouslyStatedMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IncreaseDecreaseDueToApplicationOfIFRS16Member" xlink:label="csan_IncreaseDecreaseDueToApplicationOfIFRS16Member" xlink:title="csan_IncreaseDecreaseDueToApplicationOfIFRS16Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RestatedMember" xlink:to="csan_IncreaseDecreaseDueToApplicationOfIFRS16Member" xlink:title="Definition : ifrs-full_RestatedMember to csan_IncreaseDecreaseDueToApplicationOfIFRS16Member" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RestatementMember" xlink:label="csan_RestatementMember" xlink:title="csan_RestatementMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RestatedMember" xlink:to="csan_RestatementMember" xlink:title="Definition : ifrs-full_RestatedMember to csan_RestatementMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RestatedMember" xlink:label="ifrs-full_RestatedMember_1" xlink:title="ifrs-full_RestatedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis" xlink:to="ifrs-full_RestatedMember_1" xlink:title="Definition : ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis to ifrs-full_RestatedMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfChangesInEquityLineItems" xlink:to="csan_TransactionsWithOwnersOfParentAbstract" xlink:title="Definition : ifrs-full_StatementOfChangesInEquityLineItems to csan_TransactionsWithOwnersOfParentAbstract" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_IncreaseDecreaseThroughChangeInEquityOfSubsidiaries" xlink:label="ifrs-full_IncreaseDecreaseThroughChangeInEquityOfSubsidiaries" xlink:title="ifrs-full_IncreaseDecreaseThroughChangeInEquityOfSubsidiaries"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_TransactionsWithOwnersOfParentAbstract" xlink:to="ifrs-full_IncreaseDecreaseThroughChangeInEquityOfSubsidiaries" xlink:title="Definition : csan_TransactionsWithOwnersOfParentAbstract to ifrs-full_IncreaseDecreaseThroughChangeInEquityOfSubsidiaries" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_IncreaseDecreaseThroughTransactionsWithOwners" xlink:label="ifrs-full_IncreaseDecreaseThroughTransactionsWithOwners" xlink:title="ifrs-full_IncreaseDecreaseThroughTransactionsWithOwners"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfChangesInEquityLineItems" xlink:to="ifrs-full_IncreaseDecreaseThroughTransactionsWithOwners" xlink:title="Definition : ifrs-full_StatementOfChangesInEquityLineItems to ifrs-full_IncreaseDecreaseThroughTransactionsWithOwners" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:label="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="ifrs-full_SignificantInvestmentsInSubsidiariesAxis"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="ifrs-full_SubsidiariesMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to ifrs-full_SubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RezendeBarbosaSaMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RezendeBarbosaSaMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PaylySolucoesDePagamentosSaMember" xlink:label="csan_PaylySolucoesDePagamentosSaMember" xlink:title="csan_PaylySolucoesDePagamentosSaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_PaylySolucoesDePagamentosSaMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_PaylySolucoesDePagamentosSaMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfShareCapitalAxis" xlink:label="ifrs-full_ClassesOfShareCapitalAxis" xlink:title="ifrs-full_ClassesOfShareCapitalAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_StatementTable" xlink:to="ifrs-full_ClassesOfShareCapitalAxis" xlink:title="Definition : csan_StatementTable to ifrs-full_ClassesOfShareCapitalAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfShareCapitalMember" xlink:label="ifrs-full_ClassesOfShareCapitalMember" xlink:title="ifrs-full_ClassesOfShareCapitalMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfShareCapitalAxis" xlink:to="ifrs-full_ClassesOfShareCapitalMember" xlink:title="Definition : ifrs-full_ClassesOfShareCapitalAxis to ifrs-full_ClassesOfShareCapitalMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PreferenceSharesMember" xlink:label="ifrs-full_PreferenceSharesMember" xlink:title="ifrs-full_PreferenceSharesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfShareCapitalMember" xlink:to="ifrs-full_PreferenceSharesMember" xlink:title="Definition : ifrs-full_ClassesOfShareCapitalMember to ifrs-full_PreferenceSharesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_OrdinarySharesMember" xlink:label="ifrs-full_OrdinarySharesMember" xlink:title="ifrs-full_OrdinarySharesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfShareCapitalMember" xlink:to="ifrs-full_OrdinarySharesMember" xlink:title="Definition : ifrs-full_ClassesOfShareCapitalMember to ifrs-full_OrdinarySharesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfShareCapitalMember" xlink:label="ifrs-full_ClassesOfShareCapitalMember_1" xlink:title="ifrs-full_ClassesOfShareCapitalMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfShareCapitalAxis" xlink:to="ifrs-full_ClassesOfShareCapitalMember_1" xlink:title="Definition : ifrs-full_ClassesOfShareCapitalAxis to ifrs-full_ClassesOfShareCapitalMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_StatementTable" xlink:to="ifrs-full_CounterpartiesAxis" xlink:title="Definition : csan_StatementTable to ifrs-full_CounterpartiesAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CounterpartiesMember" xlink:label="ifrs-full_CounterpartiesMember" xlink:title="ifrs-full_CounterpartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CounterpartiesAxis" xlink:to="ifrs-full_CounterpartiesMember" xlink:title="Definition : ifrs-full_CounterpartiesAxis to ifrs-full_CounterpartiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLogsticaMember" xlink:label="csan_CosanLogsticaMember" xlink:title="csan_CosanLogsticaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_CounterpartiesMember" xlink:to="csan_CosanLogsticaMember" xlink:title="Definition : ifrs-full_CounterpartiesMember to csan_CosanLogsticaMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanSAMember" xlink:label="csan_CosanSAMember" xlink:title="csan_CosanSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_CounterpartiesMember" xlink:to="csan_CosanSAMember" xlink:title="Definition : ifrs-full_CounterpartiesMember to csan_CosanSAMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CounterpartiesMember" xlink:label="ifrs-full_CounterpartiesMember_1" xlink:title="ifrs-full_CounterpartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_CounterpartiesAxis" xlink:to="ifrs-full_CounterpartiesMember_1" xlink:title="Definition : ifrs-full_CounterpartiesAxis to ifrs-full_CounterpartiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:label="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:title="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_StatementTable" xlink:to="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:title="Definition : csan_StatementTable to ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PropertyPlantAndEquipmentMember" xlink:label="ifrs-full_PropertyPlantAndEquipmentMember" xlink:title="ifrs-full_PropertyPlantAndEquipmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:to="ifrs-full_PropertyPlantAndEquipmentMember" xlink:title="Definition : ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis to ifrs-full_PropertyPlantAndEquipmentMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="ifrs-full_ConstructionInProgressMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to ifrs-full_ConstructionInProgressMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PropertyPlantAndEquipmentMember" xlink:label="ifrs-full_PropertyPlantAndEquipmentMember_1" xlink:title="ifrs-full_PropertyPlantAndEquipmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:to="ifrs-full_PropertyPlantAndEquipmentMember_1" xlink:title="Definition : ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis to ifrs-full_PropertyPlantAndEquipmentMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_NorthSouthRailroadConcessionAgreementMember" xlink:label="csan_NorthSouthRailroadConcessionAgreementMember" xlink:title="csan_NorthSouthRailroadConcessionAgreementMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_TypeOfArrangementsMember" xlink:to="csan_NorthSouthRailroadConcessionAgreementMember" xlink:title="Definition : csan_TypeOfArrangementsMember to csan_NorthSouthRailroadConcessionAgreementMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OtherLeaseAgreementsMember" xlink:label="csan_OtherLeaseAgreementsMember" xlink:title="csan_OtherLeaseAgreementsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_TypeOfArrangementsMember" xlink:to="csan_OtherLeaseAgreementsMember" xlink:title="Definition : csan_TypeOfArrangementsMember to csan_OtherLeaseAgreementsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_TaxAssetsRecognitionRelatedToExclusionOfTaxOnSalesAndServices" xlink:label="csan_TaxAssetsRecognitionRelatedToExclusionOfTaxOnSalesAndServices" xlink:title="csan_TaxAssetsRecognitionRelatedToExclusionOfTaxOnSalesAndServices"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IntangibleAssetsAdditions" xlink:label="csan_IntangibleAssetsAdditions" xlink:title="csan_IntangibleAssetsAdditions"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_StatementLineItems" xlink:to="csan_IntangibleAssetsAdditions" xlink:title="Definition : csan_StatementLineItems to csan_IntangibleAssetsAdditions" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_AdditionsToRightofuseAssets" xlink:label="ifrs-full_AdditionsToRightofuseAssets" xlink:title="ifrs-full_AdditionsToRightofuseAssets"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_StatementLineItems" xlink:to="ifrs-full_AdditionsToRightofuseAssets" xlink:title="Definition : csan_StatementLineItems to ifrs-full_AdditionsToRightofuseAssets" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CapitalContributionCapitalizationOfExpenses" xlink:label="csan_CapitalContributionCapitalizationOfExpenses" xlink:title="csan_CapitalContributionCapitalizationOfExpenses"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_StatementLineItems" xlink:to="csan_CapitalContributionCapitalizationOfExpenses" xlink:title="Definition : csan_StatementLineItems to csan_CapitalContributionCapitalizationOfExpenses" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_NonCashSettlementOfReceivables" xlink:label="csan_NonCashSettlementOfReceivables" xlink:title="csan_NonCashSettlementOfReceivables"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_StatementLineItems" xlink:to="csan_NonCashSettlementOfReceivables" xlink:title="Definition : csan_StatementLineItems to csan_NonCashSettlementOfReceivables" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_InvestmentAccountedForUsingEquityMethod" xlink:label="ifrs-full_InvestmentAccountedForUsingEquityMethod" xlink:title="ifrs-full_InvestmentAccountedForUsingEquityMethod"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_IncreaseDecreaseInContingentConsiderationAssetLiability" xlink:label="ifrs-full_IncreaseDecreaseInContingentConsiderationAssetLiability" xlink:title="ifrs-full_IncreaseDecreaseInContingentConsiderationAssetLiability"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_StatementLineItems" xlink:to="ifrs-full_IncreaseDecreaseInContingentConsiderationAssetLiability" xlink:title="Definition : csan_StatementLineItems to ifrs-full_IncreaseDecreaseInContingentConsiderationAssetLiability" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_StatementLineItems" xlink:to="ifrs-full_NumberOfInstrumentsOrInterestsIssuedOrIssuable" xlink:title="Definition : csan_StatementLineItems to ifrs-full_NumberOfInstrumentsOrInterestsIssuedOrIssuable" xlink:type="arc" use="optional" order="10" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AccountsPayable" xlink:label="csan_AccountsPayable" xlink:title="csan_AccountsPayable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_StatementLineItems" xlink:to="csan_AccountsPayable" xlink:title="Definition : csan_StatementLineItems to csan_AccountsPayable" xlink:type="arc" use="optional" order="11" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/ShareBasedPaymentTables">
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_StatementLineItems" xlink:to="ifrs-full_DisclosureOfIndirectMeasurementOfFairValueOfGoodsOrServicesReceivedShareOptionsGrantedDuringPeriodExplanatory" xlink:title="Definition : csan_StatementLineItems to ifrs-full_DisclosureOfIndirectMeasurementOfFairValueOfGoodsOrServicesReceivedShareOptionsGrantedDuringPeriodExplanatory" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfNumberAndWeightedAverageExercisePricesOfShareOptionsExplanatory" xlink:label="ifrs-full_DisclosureOfNumberAndWeightedAverageExercisePricesOfShareOptionsExplanatory" xlink:title="ifrs-full_DisclosureOfNumberAndWeightedAverageExercisePricesOfShareOptionsExplanatory"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_StatementLineItems" xlink:to="ifrs-full_DisclosureOfNumberAndWeightedAverageExercisePricesOfShareOptionsExplanatory" xlink:title="Definition : csan_StatementLineItems to ifrs-full_DisclosureOfNumberAndWeightedAverageExercisePricesOfShareOptionsExplanatory" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfNumberAndWeightedAverageRemainingContractualLifeOfOutstandingShareOptionsExplanatory" xlink:label="ifrs-full_DisclosureOfNumberAndWeightedAverageRemainingContractualLifeOfOutstandingShareOptionsExplanatory" xlink:title="ifrs-full_DisclosureOfNumberAndWeightedAverageRemainingContractualLifeOfOutstandingShareOptionsExplanatory"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_StatementLineItems" xlink:to="ifrs-full_DisclosureOfNumberAndWeightedAverageRemainingContractualLifeOfOutstandingShareOptionsExplanatory" xlink:title="Definition : csan_StatementLineItems to ifrs-full_DisclosureOfNumberAndWeightedAverageRemainingContractualLifeOfOutstandingShareOptionsExplanatory" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ExplanationOfEffectOfSharebasedPaymentsOnProfitOrLoss" xlink:label="ifrs-full_ExplanationOfEffectOfSharebasedPaymentsOnProfitOrLoss" xlink:title="ifrs-full_ExplanationOfEffectOfSharebasedPaymentsOnProfitOrLoss"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_StatementLineItems" xlink:to="ifrs-full_ExplanationOfEffectOfSharebasedPaymentsOnProfitOrLoss" xlink:title="Definition : csan_StatementLineItems to ifrs-full_ExplanationOfEffectOfSharebasedPaymentsOnProfitOrLoss" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="csan_StatementLineItems" xlink:to="csan_StatementTable" xlink:title="Definition : csan_StatementLineItems to csan_StatementTable" xlink:type="arc" use="optional" order="4" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:label="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="ifrs-full_SignificantInvestmentsInSubsidiariesAxis"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanSAIndustriaeComercioMember" xlink:label="csan_CosanSAIndustriaeComercioMember" xlink:title="csan_CosanSAIndustriaeComercioMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanSAIndustriaeComercioMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanSAIndustriaeComercioMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:to="ifrs-full_SharebasedPaymentArrangementsMember" xlink:title="Definition : ifrs-full_TypesOfSharebasedPaymentArrangementsAxis to ifrs-full_SharebasedPaymentArrangementsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SharebasedPaymentArrangementsMember" xlink:to="csan_EquitysettledPlansMember" xlink:title="Definition : ifrs-full_SharebasedPaymentArrangementsMember to csan_EquitysettledPlansMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SharebasedPaymentArrangementsMember" xlink:label="ifrs-full_SharebasedPaymentArrangementsMember_1" xlink:title="ifrs-full_SharebasedPaymentArrangementsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:to="ifrs-full_SharebasedPaymentArrangementsMember_1" xlink:title="Definition : ifrs-full_TypesOfSharebasedPaymentArrangementsAxis to ifrs-full_SharebasedPaymentArrangementsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/OperationsAdditionalInformationDetail">
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfBackgroundAndOperationsLineItems" xlink:to="ifrs-full_ProportionOfOwnershipInterestInSubsidiary" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsLineItems to ifrs-full_ProportionOfOwnershipInterestInSubsidiary" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_AcquisitiondateFairValueOfTotalConsiderationTransferred" xlink:label="ifrs-full_AcquisitiondateFairValueOfTotalConsiderationTransferred" xlink:title="ifrs-full_AcquisitiondateFairValueOfTotalConsiderationTransferred"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_AcquisitionsThroughBusinessCombinationsIntangibleAssetsAndGoodwill" xlink:label="ifrs-full_AcquisitionsThroughBusinessCombinationsIntangibleAssetsAndGoodwill" xlink:title="ifrs-full_AcquisitionsThroughBusinessCombinationsIntangibleAssetsAndGoodwill"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PortionOfConsiderationPaidReceivedConsistingOfCashAndCashEquivalents" xlink:label="ifrs-full_PortionOfConsiderationPaidReceivedConsistingOfCashAndCashEquivalents" xlink:title="ifrs-full_PortionOfConsiderationPaidReceivedConsistingOfCashAndCashEquivalents"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_IncreaseDecreaseInContingentConsiderationAssetLiability" xlink:label="ifrs-full_IncreaseDecreaseInContingentConsiderationAssetLiability" xlink:title="ifrs-full_IncreaseDecreaseInContingentConsiderationAssetLiability"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfBackgroundAndOperationsLineItems" xlink:to="ifrs-full_IncreaseDecreaseInContingentConsiderationAssetLiability" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsLineItems to ifrs-full_IncreaseDecreaseInContingentConsiderationAssetLiability" xlink:type="arc" use="optional" order="10" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CashContributions" xlink:label="csan_CashContributions" xlink:title="csan_CashContributions"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfBackgroundAndOperationsLineItems" xlink:to="csan_CashContributions" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsLineItems to csan_CashContributions" xlink:type="arc" use="optional" order="11" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PercentageOfIssuanceOfNewCommonShares" xlink:label="csan_PercentageOfIssuanceOfNewCommonShares" xlink:title="csan_PercentageOfIssuanceOfNewCommonShares"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfBackgroundAndOperationsLineItems" xlink:to="csan_PercentageOfIssuanceOfNewCommonShares" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsLineItems to csan_PercentageOfIssuanceOfNewCommonShares" xlink:type="arc" use="optional" order="12" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CapitalContribution" xlink:label="csan_CapitalContribution" xlink:title="csan_CapitalContribution"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfBackgroundAndOperationsLineItems" xlink:to="csan_CapitalContribution" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsLineItems to csan_CapitalContribution" xlink:type="arc" use="optional" order="13" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ResolutionAmountApproved" xlink:label="csan_ResolutionAmountApproved" xlink:title="csan_ResolutionAmountApproved"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfBackgroundAndOperationsLineItems" xlink:to="csan_ResolutionAmountApproved" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsLineItems to csan_ResolutionAmountApproved" xlink:type="arc" use="optional" order="14" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_InvestmentInJointVenture" xlink:label="csan_InvestmentInJointVenture" xlink:title="csan_InvestmentInJointVenture"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfBackgroundAndOperationsLineItems" xlink:to="csan_GainLossFromFormationOfJointVenture" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsLineItems to csan_GainLossFromFormationOfJointVenture" xlink:type="arc" use="optional" order="16" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ChangesInEquity" xlink:label="ifrs-full_ChangesInEquity" xlink:title="ifrs-full_ChangesInEquity"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfBackgroundAndOperationsLineItems" xlink:to="ifrs-full_ChangesInEquity" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsLineItems to ifrs-full_ChangesInEquity" xlink:type="arc" use="optional" order="17" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ContractualTerm" xlink:label="csan_ContractualTerm" xlink:title="csan_ContractualTerm"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BidAmountAdjustedWithContratualParameters" xlink:label="csan_BidAmountAdjustedWithContratualParameters" xlink:title="csan_BidAmountAdjustedWithContratualParameters"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfBackgroundAndOperationsLineItems" xlink:to="csan_BidAmountAdjustedWithContratualParameters" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsLineItems to csan_BidAmountAdjustedWithContratualParameters" xlink:type="arc" use="optional" order="19" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BidAmount" xlink:label="csan_BidAmount" xlink:title="csan_BidAmount"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfBackgroundAndOperationsLineItems" xlink:to="csan_BidAmount" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsLineItems to csan_BidAmount" xlink:type="arc" use="optional" order="20" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProportionOfOwnershipInterestInJointVenture" xlink:label="ifrs-full_ProportionOfOwnershipInterestInJointVenture" xlink:title="ifrs-full_ProportionOfOwnershipInterestInJointVenture"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PaymentsForAuction" xlink:label="csan_PaymentsForAuction" xlink:title="csan_PaymentsForAuction"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfBackgroundAndOperationsLineItems" xlink:to="csan_PaymentsForAuction" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsLineItems to csan_PaymentsForAuction" xlink:type="arc" use="optional" order="22" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PercentageOfCashPaymentInAuction" xlink:label="csan_PercentageOfCashPaymentInAuction" xlink:title="csan_PercentageOfCashPaymentInAuction"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_NumberOfPurchaseOptions" xlink:label="csan_NumberOfPurchaseOptions" xlink:title="csan_NumberOfPurchaseOptions"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfBackgroundAndOperationsLineItems" xlink:to="csan_NumberOfPurchaseOptions" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsLineItems to csan_NumberOfPurchaseOptions" xlink:type="arc" use="optional" order="24" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ProceedsFromSaleOfEquitySharesHeldByControlledTrust" xlink:label="csan_ProceedsFromSaleOfEquitySharesHeldByControlledTrust" xlink:title="csan_ProceedsFromSaleOfEquitySharesHeldByControlledTrust"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfBackgroundAndOperationsLineItems" xlink:to="csan_ProceedsFromSaleOfEquitySharesHeldByControlledTrust" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsLineItems to csan_ProceedsFromSaleOfEquitySharesHeldByControlledTrust" xlink:type="arc" use="optional" order="25" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfBackgroundAndOperationsTable" xlink:label="csan_DisclosureOfBackgroundAndOperationsTable" xlink:title="csan_DisclosureOfBackgroundAndOperationsTable"/>
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<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:title="dei_LegalEntityAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfBackgroundAndOperationsTable" xlink:to="dei_LegalEntityAxis" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsTable to dei_LegalEntityAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:title="dei_EntityDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" xlink:title="Definition : dei_LegalEntityAxis to dei_EntityDomain" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanSAMember" xlink:label="csan_CosanSAMember" xlink:title="csan_CosanSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="csan_CosanSAMember" xlink:title="Definition : dei_EntityDomain to csan_CosanSAMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLogisticaSAMember" xlink:label="csan_CosanLogisticaSAMember" xlink:title="csan_CosanLogisticaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="csan_CosanLogisticaSAMember" xlink:title="Definition : dei_EntityDomain to csan_CosanLogisticaSAMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain_1" xlink:title="dei_EntityDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain_1" xlink:title="Definition : dei_LegalEntityAxis to dei_EntityDomain" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ComponentsOfEquityAxis" xlink:label="ifrs-full_ComponentsOfEquityAxis" xlink:title="ifrs-full_ComponentsOfEquityAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfBackgroundAndOperationsTable" xlink:to="ifrs-full_ComponentsOfEquityAxis" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsTable to ifrs-full_ComponentsOfEquityAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EquityMember" xlink:label="ifrs-full_EquityMember" xlink:title="ifrs-full_EquityMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ComponentsOfEquityAxis" xlink:to="ifrs-full_EquityMember" xlink:title="Definition : ifrs-full_ComponentsOfEquityAxis to ifrs-full_EquityMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CapitalReserveMember" xlink:label="ifrs-full_CapitalReserveMember" xlink:title="ifrs-full_CapitalReserveMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EquityMember" xlink:to="ifrs-full_CapitalReserveMember" xlink:title="Definition : ifrs-full_EquityMember to ifrs-full_CapitalReserveMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EquityMember" xlink:label="ifrs-full_EquityMember_1" xlink:title="ifrs-full_EquityMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ComponentsOfEquityAxis" xlink:to="ifrs-full_EquityMember_1" xlink:title="Definition : ifrs-full_ComponentsOfEquityAxis to ifrs-full_EquityMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ResolutionTypeAxis" xlink:label="csan_ResolutionTypeAxis" xlink:title="csan_ResolutionTypeAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfBackgroundAndOperationsTable" xlink:to="csan_ResolutionTypeAxis" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsTable to csan_ResolutionTypeAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ResolutiontypeDomain" xlink:label="csan_ResolutiontypeDomain" xlink:title="csan_ResolutiontypeDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="csan_ResolutionTypeAxis" xlink:to="csan_ResolutiontypeDomain" xlink:title="Definition : csan_ResolutionTypeAxis to csan_ResolutiontypeDomain" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_Arsesp933ResolutionMember" xlink:label="csan_Arsesp933ResolutionMember" xlink:title="csan_Arsesp933ResolutionMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_ResolutiontypeDomain" xlink:to="csan_Arsesp933ResolutionMember" xlink:title="Definition : csan_ResolutiontypeDomain to csan_Arsesp933ResolutionMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ResolutiontypeDomain" xlink:label="csan_ResolutiontypeDomain_1" xlink:title="csan_ResolutiontypeDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="csan_ResolutionTypeAxis" xlink:to="csan_ResolutiontypeDomain_1" xlink:title="Definition : csan_ResolutionTypeAxis to csan_ResolutiontypeDomain" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_TypesOfRisksMember" xlink:to="ifrs-full_CreditRiskMember" xlink:title="Definition : ifrs-full_TypesOfRisksMember to ifrs-full_CreditRiskMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SeniorNotesDue2029Member" xlink:label="csan_SeniorNotesDue2029Member" xlink:title="csan_SeniorNotesDue2029Member"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ComgasMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ComgasMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoSAMember" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
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<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:title="dei_EntityDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" xlink:title="Definition : dei_LegalEntityAxis to dei_EntityDomain" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanSAMember" xlink:label="csan_CosanSAMember" xlink:title="csan_CosanSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="csan_CosanSAMember" xlink:title="Definition : dei_EntityDomain to csan_CosanSAMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLimitedMember" xlink:label="csan_CosanLimitedMember" xlink:title="csan_CosanLimitedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="csan_CosanLimitedMember" xlink:title="Definition : dei_EntityDomain to csan_CosanLimitedMember" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain_1" xlink:title="dei_EntityDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain_1" xlink:title="Definition : dei_LegalEntityAxis to dei_EntityDomain" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_HedgingInstrumentAssets" xlink:label="ifrs-full_HedgingInstrumentAssets" xlink:title="ifrs-full_HedgingInstrumentAssets"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfDetailedInformationAboutHedgingInstrumentsLineItems" xlink:to="ifrs-full_HedgingInstrumentAssets" xlink:title="Definition : ifrs-full_DisclosureOfDetailedInformationAboutHedgingInstrumentsLineItems to ifrs-full_HedgingInstrumentAssets" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_HedgingInstrumentLiabilities" xlink:label="ifrs-full_HedgingInstrumentLiabilities" xlink:title="ifrs-full_HedgingInstrumentLiabilities"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfDetailedInformationAboutHedgingInstrumentsLineItems" xlink:to="ifrs-full_HedgingInstrumentLiabilities" xlink:title="Definition : ifrs-full_DisclosureOfDetailedInformationAboutHedgingInstrumentsLineItems to ifrs-full_HedgingInstrumentLiabilities" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GainLossOnChangeInFairValueOfHedgingInstrumentUsedAsBasisForRecognisingHedgeIneffectiveness" xlink:label="ifrs-full_GainLossOnChangeInFairValueOfHedgingInstrumentUsedAsBasisForRecognisingHedgeIneffectiveness" xlink:title="ifrs-full_GainLossOnChangeInFairValueOfHedgingInstrumentUsedAsBasisForRecognisingHedgeIneffectiveness"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfDetailedInformationAboutHedgingInstrumentsTable" xlink:label="ifrs-full_DisclosureOfDetailedInformationAboutHedgingInstrumentsTable" xlink:title="ifrs-full_DisclosureOfDetailedInformationAboutHedgingInstrumentsTable"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfDetailedInformationAboutHedgingInstrumentsTable" xlink:to="ifrs-full_TypesOfRisksAxis" xlink:title="Definition : ifrs-full_DisclosureOfDetailedInformationAboutHedgingInstrumentsTable to ifrs-full_TypesOfRisksAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TypesOfRisksMember" xlink:label="ifrs-full_TypesOfRisksMember" xlink:title="ifrs-full_TypesOfRisksMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_TypesOfRisksAxis" xlink:to="ifrs-full_TypesOfRisksMember" xlink:title="Definition : ifrs-full_TypesOfRisksAxis to ifrs-full_TypesOfRisksMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CommodityPriceRiskMember" xlink:label="ifrs-full_CommodityPriceRiskMember" xlink:title="ifrs-full_CommodityPriceRiskMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_TypesOfRisksMember" xlink:to="ifrs-full_CommodityPriceRiskMember" xlink:title="Definition : ifrs-full_TypesOfRisksMember to ifrs-full_CommodityPriceRiskMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TypesOfRisksMember" xlink:label="ifrs-full_TypesOfRisksMember_1" xlink:title="ifrs-full_TypesOfRisksMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_TypesOfRisksAxis" xlink:to="ifrs-full_TypesOfRisksMember_1" xlink:title="Definition : ifrs-full_TypesOfRisksAxis to ifrs-full_TypesOfRisksMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ProductsAndServicesAxis" xlink:to="ifrs-full_ProductsAndServicesMember" xlink:title="Definition : ifrs-full_ProductsAndServicesAxis to ifrs-full_ProductsAndServicesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="ifrs-full_ElectricityDistributionMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to ifrs-full_ElectricityDistributionMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProductsAndServicesMember" xlink:label="ifrs-full_ProductsAndServicesMember_1" xlink:title="ifrs-full_ProductsAndServicesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ProductsAndServicesAxis" xlink:to="ifrs-full_ProductsAndServicesMember_1" xlink:title="Definition : ifrs-full_ProductsAndServicesAxis to ifrs-full_ProductsAndServicesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfOperatingSegmentsTable" xlink:label="ifrs-full_DisclosureOfOperatingSegmentsTable" xlink:title="ifrs-full_DisclosureOfOperatingSegmentsTable"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_GeographicalAreasAxis" xlink:to="ifrs-full_GeographicalAreasMember" xlink:title="Definition : ifrs-full_GeographicalAreasAxis to ifrs-full_GeographicalAreasMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CountryOfDomicileMember" xlink:label="ifrs-full_CountryOfDomicileMember" xlink:title="ifrs-full_CountryOfDomicileMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_GeographicalAreasMember" xlink:to="ifrs-full_CountryOfDomicileMember" xlink:title="Definition : ifrs-full_GeographicalAreasMember to ifrs-full_CountryOfDomicileMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ForeignCountriesMember" xlink:label="ifrs-full_ForeignCountriesMember" xlink:title="ifrs-full_ForeignCountriesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_GeographicalAreasMember" xlink:to="ifrs-full_ForeignCountriesMember" xlink:title="Definition : ifrs-full_GeographicalAreasMember to ifrs-full_ForeignCountriesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GeographicalAreasMember" xlink:label="ifrs-full_GeographicalAreasMember_1" xlink:title="ifrs-full_GeographicalAreasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_GeographicalAreasAxis" xlink:to="ifrs-full_GeographicalAreasMember_1" xlink:title="Definition : ifrs-full_GeographicalAreasAxis to ifrs-full_GeographicalAreasMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsTable" xlink:to="ifrs-full_SegmentConsolidationItemsAxis" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsTable to ifrs-full_SegmentConsolidationItemsAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:label="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:title="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SegmentConsolidationItemsAxis" xlink:to="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:title="Definition : ifrs-full_SegmentConsolidationItemsAxis to ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:to="csan_DeconsolidationOfJointVenturesMember" xlink:title="Definition : ifrs-full_EntitysTotalForSegmentConsolidationItemsMember to csan_DeconsolidationOfJointVenturesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EliminationOfIntersegmentAmountsMember" xlink:label="ifrs-full_EliminationOfIntersegmentAmountsMember" xlink:title="ifrs-full_EliminationOfIntersegmentAmountsMember"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:to="ifrs-full_OperatingSegmentsMember" xlink:title="Definition : ifrs-full_EntitysTotalForSegmentConsolidationItemsMember to ifrs-full_OperatingSegmentsMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_UnallocatedAmountsMember" xlink:label="ifrs-full_UnallocatedAmountsMember" xlink:title="ifrs-full_UnallocatedAmountsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:to="ifrs-full_UnallocatedAmountsMember" xlink:title="Definition : ifrs-full_EntitysTotalForSegmentConsolidationItemsMember to ifrs-full_UnallocatedAmountsMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:label="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember_1" xlink:title="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SegmentConsolidationItemsAxis" xlink:to="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember_1" xlink:title="Definition : ifrs-full_SegmentConsolidationItemsAxis to ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SegmentsAxis" xlink:label="ifrs-full_SegmentsAxis" xlink:title="ifrs-full_SegmentsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsTable" xlink:to="ifrs-full_SegmentsAxis" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsTable to ifrs-full_SegmentsAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SegmentsMember" xlink:label="ifrs-full_SegmentsMember" xlink:title="ifrs-full_SegmentsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SegmentsAxis" xlink:to="ifrs-full_SegmentsMember" xlink:title="Definition : ifrs-full_SegmentsAxis to ifrs-full_SegmentsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CompanhiaDeGasDeSaoPauloMember" xlink:label="csan_CompanhiaDeGasDeSaoPauloMember" xlink:title="csan_CompanhiaDeGasDeSaoPauloMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_CompanhiaDeGasDeSaoPauloMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_CompanhiaDeGasDeSaoPauloMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanCorporateMember" xlink:label="csan_CosanCorporateMember" xlink:title="csan_CosanCorporateMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_CosanCorporateMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_CosanCorporateMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LogisticsMember" xlink:label="csan_LogisticsMember" xlink:title="csan_LogisticsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_LogisticsMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_LogisticsMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_MooveMember" xlink:label="csan_MooveMember" xlink:title="csan_MooveMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_MooveMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_MooveMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RaizenCombustiveisMember" xlink:label="csan_RaizenCombustiveisMember" xlink:title="csan_RaizenCombustiveisMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_RaizenCombustiveisMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_RaizenCombustiveisMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RaizenEnergiaMember" xlink:label="csan_RaizenEnergiaMember" xlink:title="csan_RaizenEnergiaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_RaizenEnergiaMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_RaizenEnergiaMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_GasAndEnergyMember" xlink:label="csan_GasAndEnergyMember" xlink:title="csan_GasAndEnergyMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_GasAndEnergyMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_GasAndEnergyMember" xlink:type="arc" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SegmentsMember" xlink:label="ifrs-full_SegmentsMember_1" xlink:title="ifrs-full_SegmentsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SegmentsAxis" xlink:to="ifrs-full_SegmentsMember_1" xlink:title="Definition : ifrs-full_SegmentsAxis to ifrs-full_SegmentsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis" xlink:title="srt_StatementGeographicalAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsTable" xlink:to="srt_StatementGeographicalAxis" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsTable to srt_StatementGeographicalAxis" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain" xlink:title="srt_SegmentGeographicalDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" xlink:title="Definition : srt_StatementGeographicalAxis to srt_SegmentGeographicalDomain" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_AR" xlink:label="country_AR" xlink:title="country_AR"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="country_AR" xlink:title="Definition : srt_SegmentGeographicalDomain to country_AR" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_BR" xlink:label="country_BR" xlink:title="country_BR"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="country_BR" xlink:title="Definition : srt_SegmentGeographicalDomain to country_BR" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain_1" xlink:title="srt_SegmentGeographicalDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain_1" xlink:title="Definition : srt_StatementGeographicalAxis to srt_SegmentGeographicalDomain" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsLineItems" xlink:to="ifrs-full_FinanceCosts" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsLineItems to ifrs-full_FinanceCosts" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_FinanceIncome" xlink:label="ifrs-full_FinanceIncome" xlink:title="ifrs-full_FinanceIncome"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsLineItems" xlink:to="ifrs-full_FinanceIncome" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsLineItems to ifrs-full_FinanceIncome" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_FinanceIncomeCost" xlink:label="ifrs-full_FinanceIncomeCost" xlink:title="ifrs-full_FinanceIncomeCost"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsLineItems" xlink:to="ifrs-full_FinanceIncomeCost" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsLineItems to ifrs-full_FinanceIncomeCost" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GainsLossesOnChangeInFairValueOfDerivatives" xlink:label="ifrs-full_GainsLossesOnChangeInFairValueOfDerivatives" xlink:title="ifrs-full_GainsLossesOnChangeInFairValueOfDerivatives"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsLineItems" xlink:to="ifrs-full_GainsLossesOnChangeInFairValueOfDerivatives" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsLineItems to ifrs-full_GainsLossesOnChangeInFairValueOfDerivatives" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GainsLossesOnExchangeDifferencesOnTranslationBeforeTax" xlink:label="ifrs-full_GainsLossesOnExchangeDifferencesOnTranslationBeforeTax" xlink:title="ifrs-full_GainsLossesOnExchangeDifferencesOnTranslationBeforeTax"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsLineItems" xlink:to="ifrs-full_GainsLossesOnExchangeDifferencesOnTranslationBeforeTax" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsLineItems to ifrs-full_GainsLossesOnExchangeDifferencesOnTranslationBeforeTax" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GrossProfit" xlink:label="ifrs-full_GrossProfit" xlink:title="ifrs-full_GrossProfit"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsLineItems" xlink:to="ifrs-full_GrossProfit" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsLineItems to ifrs-full_GrossProfit" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_GrossRevenue" xlink:label="csan_GrossRevenue" xlink:title="csan_GrossRevenue"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsLineItems" xlink:to="csan_GrossRevenue" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsLineItems to csan_GrossRevenue" xlink:type="arc" use="optional" order="8" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_IncomeTaxExpenseContinuingOperations" xlink:label="ifrs-full_IncomeTaxExpenseContinuingOperations" xlink:title="ifrs-full_IncomeTaxExpenseContinuingOperations"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsLineItems" xlink:to="ifrs-full_IncomeTaxExpenseContinuingOperations" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsLineItems to ifrs-full_IncomeTaxExpenseContinuingOperations" xlink:type="arc" use="optional" order="9" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_OtherOperatingIncomeExpense" xlink:label="ifrs-full_OtherOperatingIncomeExpense" xlink:title="ifrs-full_OtherOperatingIncomeExpense"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsLineItems" xlink:to="ifrs-full_OtherOperatingIncomeExpense" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsLineItems to ifrs-full_OtherOperatingIncomeExpense" xlink:type="arc" use="optional" order="10" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OtherSelectedDataAbstract" xlink:label="csan_OtherSelectedDataAbstract" xlink:title="csan_OtherSelectedDataAbstract"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsLineItems" xlink:to="csan_OtherSelectedDataAbstract" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsLineItems to csan_OtherSelectedDataAbstract" xlink:type="arc" use="optional" order="11" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_EarningsBeforeInterestTaxDepreciationAndAmortization" xlink:label="csan_EarningsBeforeInterestTaxDepreciationAndAmortization" xlink:title="csan_EarningsBeforeInterestTaxDepreciationAndAmortization"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_OtherSelectedDataAbstract" xlink:to="csan_EarningsBeforeInterestTaxDepreciationAndAmortization" xlink:title="Definition : csan_OtherSelectedDataAbstract to csan_EarningsBeforeInterestTaxDepreciationAndAmortization" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DepreciationAndAmortisationExpense" xlink:label="ifrs-full_DepreciationAndAmortisationExpense" xlink:title="ifrs-full_DepreciationAndAmortisationExpense"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_OtherSelectedDataAbstract" xlink:to="ifrs-full_DepreciationAndAmortisationExpense" xlink:title="Definition : csan_OtherSelectedDataAbstract to ifrs-full_DepreciationAndAmortisationExpense" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AdditionsToPropertyPlantAndEquipmentIntangibleAndContractAssets" xlink:label="csan_AdditionsToPropertyPlantAndEquipmentIntangibleAndContractAssets" xlink:title="csan_AdditionsToPropertyPlantAndEquipmentIntangibleAndContractAssets"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_OtherSelectedDataAbstract" xlink:to="csan_AdditionsToPropertyPlantAndEquipmentIntangibleAndContractAssets" xlink:title="Definition : csan_OtherSelectedDataAbstract to csan_AdditionsToPropertyPlantAndEquipmentIntangibleAndContractAssets" xlink:type="arc" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProfitLossAttributableToAbstract" xlink:label="ifrs-full_ProfitLossAttributableToAbstract" xlink:title="ifrs-full_ProfitLossAttributableToAbstract"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsLineItems" xlink:to="ifrs-full_ProfitLossAttributableToAbstract" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsLineItems to ifrs-full_ProfitLossAttributableToAbstract" xlink:type="arc" use="optional" order="12" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProfitLoss" xlink:label="ifrs-full_ProfitLoss" xlink:title="ifrs-full_ProfitLoss"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProfitLossAttributableToAbstract" xlink:to="ifrs-full_ProfitLoss" xlink:title="Definition : ifrs-full_ProfitLossAttributableToAbstract to ifrs-full_ProfitLoss" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProfitLossAttributableToNoncontrollingInterests" xlink:label="ifrs-full_ProfitLossAttributableToNoncontrollingInterests" xlink:title="ifrs-full_ProfitLossAttributableToNoncontrollingInterests"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProfitLossAttributableToAbstract" xlink:to="ifrs-full_ProfitLossAttributableToNoncontrollingInterests" xlink:title="Definition : ifrs-full_ProfitLossAttributableToAbstract to ifrs-full_ProfitLossAttributableToNoncontrollingInterests" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProfitLossAttributableToOwnersOfParent" xlink:label="ifrs-full_ProfitLossAttributableToOwnersOfParent" xlink:title="ifrs-full_ProfitLossAttributableToOwnersOfParent"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProfitLossAttributableToAbstract" xlink:to="ifrs-full_ProfitLossAttributableToOwnersOfParent" xlink:title="Definition : ifrs-full_ProfitLossAttributableToAbstract to ifrs-full_ProfitLossAttributableToOwnersOfParent" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProfitLossFromContinuingOperations" xlink:label="ifrs-full_ProfitLossFromContinuingOperations" xlink:title="ifrs-full_ProfitLossFromContinuingOperations"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsLineItems" xlink:to="ifrs-full_ProfitLossFromContinuingOperations" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsLineItems to ifrs-full_ProfitLossFromContinuingOperations" xlink:type="arc" use="optional" order="13" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProfitLossFromDiscontinuedOperations" xlink:label="ifrs-full_ProfitLossFromDiscontinuedOperations" xlink:title="ifrs-full_ProfitLossFromDiscontinuedOperations"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ReconciliationOfEarningsBeforeInterestTaxDepreciationAndAmortizationAbstract" xlink:label="csan_ReconciliationOfEarningsBeforeInterestTaxDepreciationAndAmortizationAbstract" xlink:title="csan_ReconciliationOfEarningsBeforeInterestTaxDepreciationAndAmortizationAbstract"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsTable" xlink:to="ifrs-full_SegmentConsolidationItemsAxis" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsTable to ifrs-full_SegmentConsolidationItemsAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:label="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:title="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SegmentConsolidationItemsAxis" xlink:to="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:title="Definition : ifrs-full_SegmentConsolidationItemsAxis to ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DeconsolidationEffectsIFRS11Member" xlink:label="csan_DeconsolidationEffectsIFRS11Member" xlink:title="csan_DeconsolidationEffectsIFRS11Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:to="csan_DeconsolidationEffectsIFRS11Member" xlink:title="Definition : ifrs-full_EntitysTotalForSegmentConsolidationItemsMember to csan_DeconsolidationEffectsIFRS11Member" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EliminationOfIntersegmentAmountsMember" xlink:label="ifrs-full_EliminationOfIntersegmentAmountsMember" xlink:title="ifrs-full_EliminationOfIntersegmentAmountsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:to="ifrs-full_EliminationOfIntersegmentAmountsMember" xlink:title="Definition : ifrs-full_EntitysTotalForSegmentConsolidationItemsMember to ifrs-full_EliminationOfIntersegmentAmountsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:to="ifrs-full_OperatingSegmentsMember" xlink:title="Definition : ifrs-full_EntitysTotalForSegmentConsolidationItemsMember to ifrs-full_OperatingSegmentsMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_UnallocatedAmountsMember" xlink:label="ifrs-full_UnallocatedAmountsMember" xlink:title="ifrs-full_UnallocatedAmountsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:to="ifrs-full_UnallocatedAmountsMember" xlink:title="Definition : ifrs-full_EntitysTotalForSegmentConsolidationItemsMember to ifrs-full_UnallocatedAmountsMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:label="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember_1" xlink:title="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsTable" xlink:to="ifrs-full_SegmentsAxis" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsTable to ifrs-full_SegmentsAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LogisticsMember" xlink:label="csan_LogisticsMember" xlink:title="csan_LogisticsMember"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_MooveMember" xlink:label="csan_MooveMember" xlink:title="csan_MooveMember"/>
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<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_AR" xlink:label="country_AR" xlink:title="country_AR"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GeographicalAreasMember" xlink:label="ifrs-full_GeographicalAreasMember_1" xlink:title="ifrs-full_GeographicalAreasMember"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="ifrs-full_Borrowings" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to ifrs-full_Borrowings" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CashAndCashEquivalents" xlink:label="ifrs-full_CashAndCashEquivalents" xlink:title="ifrs-full_CashAndCashEquivalents"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="ifrs-full_CashAndCashEquivalents" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to ifrs-full_CashAndCashEquivalents" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CurrentRecognisedLiabilitiesDefinedBenefitPlan" xlink:label="ifrs-full_CurrentRecognisedLiabilitiesDefinedBenefitPlan" xlink:title="ifrs-full_CurrentRecognisedLiabilitiesDefinedBenefitPlan"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="ifrs-full_CurrentRecognisedLiabilitiesDefinedBenefitPlan" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to ifrs-full_CurrentRecognisedLiabilitiesDefinedBenefitPlan" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DerivativeFinancialAssets" xlink:label="ifrs-full_DerivativeFinancialAssets" xlink:title="ifrs-full_DerivativeFinancialAssets"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="ifrs-full_DerivativeFinancialAssets" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to ifrs-full_DerivativeFinancialAssets" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DerivativeFinancialLiabilities" xlink:label="ifrs-full_DerivativeFinancialLiabilities" xlink:title="ifrs-full_DerivativeFinancialLiabilities"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="ifrs-full_DerivativeFinancialLiabilities" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to ifrs-full_DerivativeFinancialLiabilities" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LeaseLiabilitiesFinance" xlink:label="csan_LeaseLiabilitiesFinance" xlink:title="csan_LeaseLiabilitiesFinance"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="csan_LeaseLiabilitiesFinance" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to csan_LeaseLiabilitiesFinance" xlink:type="arc" use="optional" order="8" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_IntangibleAssetsAndGoodwill" xlink:label="ifrs-full_IntangibleAssetsAndGoodwill" xlink:title="ifrs-full_IntangibleAssetsAndGoodwill"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="ifrs-full_IntangibleAssetsAndGoodwill" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to ifrs-full_IntangibleAssetsAndGoodwill" xlink:type="arc" use="optional" order="9" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_Inventories" xlink:label="ifrs-full_Inventories" xlink:title="ifrs-full_Inventories"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="ifrs-full_Inventories" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to ifrs-full_Inventories" xlink:type="arc" use="optional" order="10" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_InvestmentsInAssociatesAccountedForUsingEquityMethod" xlink:label="ifrs-full_InvestmentsInAssociatesAccountedForUsingEquityMethod" xlink:title="ifrs-full_InvestmentsInAssociatesAccountedForUsingEquityMethod"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="ifrs-full_InvestmentsInAssociatesAccountedForUsingEquityMethod" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to ifrs-full_InvestmentsInAssociatesAccountedForUsingEquityMethod" xlink:type="arc" use="optional" order="11" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_InvestmentsInJointVenturesAccountedForUsingEquityMethod" xlink:label="ifrs-full_InvestmentsInJointVenturesAccountedForUsingEquityMethod" xlink:title="ifrs-full_InvestmentsInJointVenturesAccountedForUsingEquityMethod"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="ifrs-full_InvestmentsInJointVenturesAccountedForUsingEquityMethod" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to ifrs-full_InvestmentsInJointVenturesAccountedForUsingEquityMethod" xlink:type="arc" use="optional" order="12" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_MarketableSecurities1" xlink:label="csan_MarketableSecurities1" xlink:title="csan_MarketableSecurities1"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="csan_MarketableSecurities1" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to csan_MarketableSecurities1" xlink:type="arc" use="optional" order="13" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OtherCurrentAssetsOther" xlink:label="csan_OtherCurrentAssetsOther" xlink:title="csan_OtherCurrentAssetsOther"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="csan_OtherCurrentAssetsOther" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to csan_OtherCurrentAssetsOther" xlink:type="arc" use="optional" order="14" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OtherCurrentLiabilitiesClassifiedAsOther" xlink:label="csan_OtherCurrentLiabilitiesClassifiedAsOther" xlink:title="csan_OtherCurrentLiabilitiesClassifiedAsOther"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="csan_OtherCurrentLiabilitiesClassifiedAsOther" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to csan_OtherCurrentLiabilitiesClassifiedAsOther" xlink:type="arc" use="optional" order="15" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_OtherFinancialAssets" xlink:label="ifrs-full_OtherFinancialAssets" xlink:title="ifrs-full_OtherFinancialAssets"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="ifrs-full_OtherFinancialAssets" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to ifrs-full_OtherFinancialAssets" xlink:type="arc" use="optional" order="16" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OtherNonCurrentAssetsOther" xlink:label="csan_OtherNonCurrentAssetsOther" xlink:title="csan_OtherNonCurrentAssetsOther"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="csan_OtherNonCurrentAssetsOther" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to csan_OtherNonCurrentAssetsOther" xlink:type="arc" use="optional" order="17" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OtherNoncurrentLiabilitiesOther" xlink:label="csan_OtherNoncurrentLiabilitiesOther" xlink:title="csan_OtherNoncurrentLiabilitiesOther"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="csan_OtherNoncurrentLiabilitiesOther" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to csan_OtherNoncurrentLiabilitiesOther" xlink:type="arc" use="optional" order="18" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PreferredShareholdersPayableSubsidiariesNonCurrent" xlink:label="csan_PreferredShareholdersPayableSubsidiariesNonCurrent" xlink:title="csan_PreferredShareholdersPayableSubsidiariesNonCurrent"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="csan_PreferredShareholdersPayableSubsidiariesNonCurrent" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to csan_PreferredShareholdersPayableSubsidiariesNonCurrent" xlink:type="arc" use="optional" order="19" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PropertyPlantAndEquipment" xlink:label="ifrs-full_PropertyPlantAndEquipment" xlink:title="ifrs-full_PropertyPlantAndEquipment"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="ifrs-full_PropertyPlantAndEquipment" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to ifrs-full_PropertyPlantAndEquipment" xlink:type="arc" use="optional" order="20" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_TradePayable" xlink:label="csan_TradePayable" xlink:title="csan_TradePayable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="csan_TradePayable" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to csan_TradePayable" xlink:type="arc" use="optional" order="21" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TradeReceivables" xlink:label="ifrs-full_TradeReceivables" xlink:title="ifrs-full_TradeReceivables"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="ifrs-full_TradeReceivables" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to ifrs-full_TradeReceivables" xlink:type="arc" use="optional" order="22" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RightofuseAssets" xlink:label="ifrs-full_RightofuseAssets" xlink:title="ifrs-full_RightofuseAssets"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="ifrs-full_RightofuseAssets" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to ifrs-full_RightofuseAssets" xlink:type="arc" use="optional" order="23" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NoncurrentContractAssets" xlink:label="ifrs-full_NoncurrentContractAssets" xlink:title="ifrs-full_NoncurrentContractAssets"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="ifrs-full_NoncurrentContractAssets" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to ifrs-full_NoncurrentContractAssets" xlink:type="arc" use="optional" order="24" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_Liabilities" xlink:label="ifrs-full_Liabilities" xlink:title="ifrs-full_Liabilities"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="ifrs-full_Liabilities" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to ifrs-full_Liabilities" xlink:type="arc" use="optional" order="25" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CurrentSectorFinancialAssets" xlink:label="csan_CurrentSectorFinancialAssets" xlink:title="csan_CurrentSectorFinancialAssets"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="csan_CurrentSectorFinancialAssets" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to csan_CurrentSectorFinancialAssets" xlink:type="arc" order="26" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SectorFinancialLiabilities" xlink:label="csan_SectorFinancialLiabilities" xlink:title="csan_SectorFinancialLiabilities"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_StatementOfFinancialPositionAbstract" xlink:to="csan_SectorFinancialLiabilities" xlink:title="Definition : ifrs-full_StatementOfFinancialPositionAbstract to csan_SectorFinancialLiabilities" xlink:type="arc" order="27" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/SegmentInformationSummaryofNetSalesbyCustomerbySegmentDetail">
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfOperatingSegmentsLineItems" xlink:label="ifrs-full_DisclosureOfOperatingSegmentsLineItems" xlink:title="ifrs-full_DisclosureOfOperatingSegmentsLineItems"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfOperatingSegmentsTable" xlink:label="ifrs-full_DisclosureOfOperatingSegmentsTable" xlink:title="ifrs-full_DisclosureOfOperatingSegmentsTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsLineItems" xlink:to="ifrs-full_DisclosureOfOperatingSegmentsTable" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsLineItems to ifrs-full_DisclosureOfOperatingSegmentsTable" xlink:type="arc" use="optional" order="0" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GeographicalAreasAxis" xlink:label="ifrs-full_GeographicalAreasAxis" xlink:title="ifrs-full_GeographicalAreasAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsTable" xlink:to="ifrs-full_GeographicalAreasAxis" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsTable to ifrs-full_GeographicalAreasAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GeographicalAreasMember" xlink:label="ifrs-full_GeographicalAreasMember" xlink:title="ifrs-full_GeographicalAreasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_GeographicalAreasAxis" xlink:to="ifrs-full_GeographicalAreasMember" xlink:title="Definition : ifrs-full_GeographicalAreasAxis to ifrs-full_GeographicalAreasMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_NorthOperationsMember" xlink:label="csan_NorthOperationsMember" xlink:title="csan_NorthOperationsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_GeographicalAreasMember" xlink:to="csan_NorthOperationsMember" xlink:title="Definition : ifrs-full_GeographicalAreasMember to csan_NorthOperationsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SouthOperationsMember" xlink:label="csan_SouthOperationsMember" xlink:title="csan_SouthOperationsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_GeographicalAreasMember" xlink:to="csan_SouthOperationsMember" xlink:title="Definition : ifrs-full_GeographicalAreasMember to csan_SouthOperationsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GeographicalAreasMember" xlink:label="ifrs-full_GeographicalAreasMember_1" xlink:title="ifrs-full_GeographicalAreasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_GeographicalAreasAxis" xlink:to="ifrs-full_GeographicalAreasMember_1" xlink:title="Definition : ifrs-full_GeographicalAreasAxis to ifrs-full_GeographicalAreasMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProductsAndServicesAxis" xlink:label="ifrs-full_ProductsAndServicesAxis" xlink:title="ifrs-full_ProductsAndServicesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsTable" xlink:to="ifrs-full_ProductsAndServicesAxis" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsTable to ifrs-full_ProductsAndServicesAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProductsAndServicesMember" xlink:label="ifrs-full_ProductsAndServicesMember" xlink:title="ifrs-full_ProductsAndServicesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ProductsAndServicesAxis" xlink:to="ifrs-full_ProductsAndServicesMember" xlink:title="Definition : ifrs-full_ProductsAndServicesAxis to ifrs-full_ProductsAndServicesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AutomotiveMember" xlink:label="csan_AutomotiveMember" xlink:title="csan_AutomotiveMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_AutomotiveMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_AutomotiveMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BasicOilMember" xlink:label="csan_BasicOilMember" xlink:title="csan_BasicOilMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_BasicOilMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_BasicOilMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CogenerationMember" xlink:label="csan_CogenerationMember" xlink:title="csan_CogenerationMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_CogenerationMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_CogenerationMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CommercialMember" xlink:label="csan_CommercialMember" xlink:title="csan_CommercialMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_CommercialMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_CommercialMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ConstructionRevenueMember" xlink:label="csan_ConstructionRevenueMember" xlink:title="csan_ConstructionRevenueMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_ConstructionRevenueMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_ConstructionRevenueMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ContainerOperationsMember" xlink:label="csan_ContainerOperationsMember" xlink:title="csan_ContainerOperationsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_ContainerOperationsMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_ContainerOperationsMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DieselMember" xlink:label="csan_DieselMember" xlink:title="csan_DieselMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_DieselMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_DieselMember" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_EthanolMember" xlink:label="csan_EthanolMember" xlink:title="csan_EthanolMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_EthanolMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_EthanolMember" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_FinishedGoodsMember" xlink:label="csan_FinishedGoodsMember" xlink:title="csan_FinishedGoodsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_FinishedGoodsMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_FinishedGoodsMember" xlink:type="arc" use="optional" order="8" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_FuelsMember" xlink:label="csan_FuelsMember" xlink:title="csan_FuelsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_FuelsMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_FuelsMember" xlink:type="arc" use="optional" order="9" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_GasMember" xlink:label="csan_GasMember" xlink:title="csan_GasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_GasMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_GasMember" xlink:type="arc" use="optional" order="10" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IndustrialMember" xlink:label="csan_IndustrialMember" xlink:title="csan_IndustrialMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_IndustrialMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_IndustrialMember" xlink:type="arc" use="optional" order="11" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OtherMember" xlink:label="csan_OtherMember" xlink:title="csan_OtherMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_OtherMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_OtherMember" xlink:type="arc" use="optional" order="12" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ResidentialMember" xlink:label="csan_ResidentialMember" xlink:title="csan_ResidentialMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_ResidentialMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_ResidentialMember" xlink:type="arc" use="optional" order="13" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ServicesMember" xlink:label="csan_ServicesMember" xlink:title="csan_ServicesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_ServicesMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_ServicesMember" xlink:type="arc" use="optional" order="14" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SugarMember" xlink:label="csan_SugarMember" xlink:title="csan_SugarMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_SugarMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_SugarMember" xlink:type="arc" use="optional" order="15" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProductsAndServicesMember" xlink:label="ifrs-full_ProductsAndServicesMember_1" xlink:title="ifrs-full_ProductsAndServicesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ProductsAndServicesAxis" xlink:to="ifrs-full_ProductsAndServicesMember_1" xlink:title="Definition : ifrs-full_ProductsAndServicesAxis to ifrs-full_ProductsAndServicesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SegmentConsolidationItemsAxis" xlink:label="ifrs-full_SegmentConsolidationItemsAxis" xlink:title="ifrs-full_SegmentConsolidationItemsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsTable" xlink:to="ifrs-full_SegmentConsolidationItemsAxis" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsTable to ifrs-full_SegmentConsolidationItemsAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:label="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:title="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SegmentConsolidationItemsAxis" xlink:to="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:title="Definition : ifrs-full_SegmentConsolidationItemsAxis to ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DeconsolidationOfJointVenturesAdjustmentsAndEliminationsMember" xlink:label="csan_DeconsolidationOfJointVenturesAdjustmentsAndEliminationsMember" xlink:title="csan_DeconsolidationOfJointVenturesAdjustmentsAndEliminationsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:to="csan_DeconsolidationOfJointVenturesAdjustmentsAndEliminationsMember" xlink:title="Definition : ifrs-full_EntitysTotalForSegmentConsolidationItemsMember to csan_DeconsolidationOfJointVenturesAdjustmentsAndEliminationsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_OperatingSegmentsMember" xlink:label="ifrs-full_OperatingSegmentsMember" xlink:title="ifrs-full_OperatingSegmentsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:to="ifrs-full_OperatingSegmentsMember" xlink:title="Definition : ifrs-full_EntitysTotalForSegmentConsolidationItemsMember to ifrs-full_OperatingSegmentsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_UnallocatedAmountsMember" xlink:label="ifrs-full_UnallocatedAmountsMember" xlink:title="ifrs-full_UnallocatedAmountsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:to="ifrs-full_UnallocatedAmountsMember" xlink:title="Definition : ifrs-full_EntitysTotalForSegmentConsolidationItemsMember to ifrs-full_UnallocatedAmountsMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:label="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember_1" xlink:title="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SegmentConsolidationItemsAxis" xlink:to="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember_1" xlink:title="Definition : ifrs-full_SegmentConsolidationItemsAxis to ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SegmentsAxis" xlink:label="ifrs-full_SegmentsAxis" xlink:title="ifrs-full_SegmentsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsTable" xlink:to="ifrs-full_SegmentsAxis" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsTable to ifrs-full_SegmentsAxis" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SegmentsMember" xlink:label="ifrs-full_SegmentsMember" xlink:title="ifrs-full_SegmentsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SegmentsAxis" xlink:to="ifrs-full_SegmentsMember" xlink:title="Definition : ifrs-full_SegmentsAxis to ifrs-full_SegmentsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanCorporateMember" xlink:label="csan_CosanCorporateMember" xlink:title="csan_CosanCorporateMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_CosanCorporateMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_CosanCorporateMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LogisticsMember" xlink:label="csan_LogisticsMember" xlink:title="csan_LogisticsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_LogisticsMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_LogisticsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_MooveMember" xlink:label="csan_MooveMember" xlink:title="csan_MooveMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_MooveMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_MooveMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RaizenCombustiveisMember" xlink:label="csan_RaizenCombustiveisMember" xlink:title="csan_RaizenCombustiveisMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_RaizenCombustiveisMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_RaizenCombustiveisMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RaizenEnergiaMember" xlink:label="csan_RaizenEnergiaMember" xlink:title="csan_RaizenEnergiaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_RaizenEnergiaMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_RaizenEnergiaMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_GasAndEnergyMember" xlink:label="csan_GasAndEnergyMember" xlink:title="csan_GasAndEnergyMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_GasAndEnergyMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_GasAndEnergyMember" xlink:type="arc" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SegmentsMember" xlink:label="ifrs-full_SegmentsMember_1" xlink:title="ifrs-full_SegmentsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SegmentsAxis" xlink:to="ifrs-full_SegmentsMember_1" xlink:title="Definition : ifrs-full_SegmentsAxis to ifrs-full_SegmentsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TypesOfRateregulatedActivitiesAxis" xlink:label="ifrs-full_TypesOfRateregulatedActivitiesAxis" xlink:title="ifrs-full_TypesOfRateregulatedActivitiesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsTable" xlink:to="ifrs-full_TypesOfRateregulatedActivitiesAxis" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsTable to ifrs-full_TypesOfRateregulatedActivitiesAxis" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RateregulatedActivitiesMember" xlink:label="ifrs-full_RateregulatedActivitiesMember" xlink:title="ifrs-full_RateregulatedActivitiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_TypesOfRateregulatedActivitiesAxis" xlink:to="ifrs-full_RateregulatedActivitiesMember" xlink:title="Definition : ifrs-full_TypesOfRateregulatedActivitiesAxis to ifrs-full_RateregulatedActivitiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GasDistributionMember" xlink:label="ifrs-full_GasDistributionMember" xlink:title="ifrs-full_GasDistributionMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RateregulatedActivitiesMember" xlink:to="ifrs-full_GasDistributionMember" xlink:title="Definition : ifrs-full_RateregulatedActivitiesMember to ifrs-full_GasDistributionMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ElectricityDistributionMember" xlink:label="ifrs-full_ElectricityDistributionMember" xlink:title="ifrs-full_ElectricityDistributionMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RateregulatedActivitiesMember" xlink:to="ifrs-full_ElectricityDistributionMember" xlink:title="Definition : ifrs-full_RateregulatedActivitiesMember to ifrs-full_ElectricityDistributionMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RateregulatedActivitiesMember" xlink:label="ifrs-full_RateregulatedActivitiesMember_1" xlink:title="ifrs-full_RateregulatedActivitiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_TypesOfRateregulatedActivitiesAxis" xlink:to="ifrs-full_RateregulatedActivitiesMember_1" xlink:title="Definition : ifrs-full_TypesOfRateregulatedActivitiesAxis to ifrs-full_RateregulatedActivitiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOperatingSegmentsLineItems" xlink:to="ifrs-full_Revenue" xlink:title="Definition : ifrs-full_DisclosureOfOperatingSegmentsLineItems to ifrs-full_Revenue" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/SegmentInformationSummaryofInformationonGeographicalAreaDetail">
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfGeographicalAreasLineItems" xlink:label="ifrs-full_DisclosureOfGeographicalAreasLineItems" xlink:title="ifrs-full_DisclosureOfGeographicalAreasLineItems"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfGeographicalAreasTable" xlink:label="ifrs-full_DisclosureOfGeographicalAreasTable" xlink:title="ifrs-full_DisclosureOfGeographicalAreasTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ifrs-full_DisclosureOfGeographicalAreasLineItems" xlink:to="ifrs-full_DisclosureOfGeographicalAreasTable" xlink:title="Definition : ifrs-full_DisclosureOfGeographicalAreasLineItems to ifrs-full_DisclosureOfGeographicalAreasTable" xlink:type="arc" use="optional" order="0" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis" xlink:title="srt_StatementGeographicalAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfGeographicalAreasTable" xlink:to="srt_StatementGeographicalAxis" xlink:title="Definition : ifrs-full_DisclosureOfGeographicalAreasTable to srt_StatementGeographicalAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain" xlink:title="srt_SegmentGeographicalDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" xlink:title="Definition : srt_StatementGeographicalAxis to srt_SegmentGeographicalDomain" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AsiaAndOtherMember" xlink:label="csan_AsiaAndOtherMember" xlink:title="csan_AsiaAndOtherMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="csan_AsiaAndOtherMember" xlink:title="Definition : srt_SegmentGeographicalDomain to csan_AsiaAndOtherMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_BR" xlink:label="country_BR" xlink:title="country_BR"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="country_BR" xlink:title="Definition : srt_SegmentGeographicalDomain to country_BR" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_EuropeMember" xlink:label="srt_EuropeMember" xlink:title="srt_EuropeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="srt_EuropeMember" xlink:title="Definition : srt_SegmentGeographicalDomain to srt_EuropeMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_LatinAmericaMember" xlink:label="srt_LatinAmericaMember" xlink:title="srt_LatinAmericaMember"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_FinancialLiabilitiesCategoryMember" xlink:to="ifrs-full_FinancialLiabilitiesAtAmortisedCostCategoryMember" xlink:title="Definition : ifrs-full_FinancialLiabilitiesCategoryMember to ifrs-full_FinancialLiabilitiesAtAmortisedCostCategoryMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_FinancialLiabilitiesCategoryMember" xlink:to="ifrs-full_FinancialLiabilitiesAtFairValueThroughProfitOrLossCategoryMember" xlink:title="Definition : ifrs-full_FinancialLiabilitiesCategoryMember to ifrs-full_FinancialLiabilitiesAtFairValueThroughProfitOrLossCategoryMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfFinancialInstrumentsAxis" xlink:to="ifrs-full_ClassesOfFinancialInstrumentsMember" xlink:title="Definition : ifrs-full_ClassesOfFinancialInstrumentsAxis to ifrs-full_ClassesOfFinancialInstrumentsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfFinancialInstrumentsMember" xlink:to="csan_TradePayablesMember" xlink:title="Definition : ifrs-full_ClassesOfFinancialInstrumentsMember to csan_TradePayablesMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfFinancialResourcesLineItems" xlink:to="csan_ContractExpiryDate" xlink:title="Definition : csan_DisclosureOfFinancialResourcesLineItems to csan_ContractExpiryDate" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="csan_DisclosureOfFinancialResourcesLineItems" xlink:to="csan_DisclosureOfFinancialResourcesTable" xlink:title="Definition : csan_DisclosureOfFinancialResourcesLineItems to csan_DisclosureOfFinancialResourcesTable" xlink:type="arc" use="optional" order="7" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BorrowingsByNameAxis" xlink:label="ifrs-full_BorrowingsByNameAxis" xlink:title="ifrs-full_BorrowingsByNameAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfFinancialResourcesTable" xlink:to="ifrs-full_BorrowingsByNameAxis" xlink:title="Definition : csan_DisclosureOfFinancialResourcesTable to ifrs-full_BorrowingsByNameAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BorrowingsByNameMember" xlink:label="ifrs-full_BorrowingsByNameMember" xlink:title="ifrs-full_BorrowingsByNameMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_BorrowingsByNameAxis" xlink:to="ifrs-full_BorrowingsByNameMember" xlink:title="Definition : ifrs-full_BorrowingsByNameAxis to ifrs-full_BorrowingsByNameMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BNDESMember" xlink:label="csan_BNDESMember" xlink:title="csan_BNDESMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_BNDESMember" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_BNDESMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ThreeBrazilianFinancialInstitutionsMember" xlink:label="csan_ThreeBrazilianFinancialInstitutionsMember" xlink:title="csan_ThreeBrazilianFinancialInstitutionsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_ThreeBrazilianFinancialInstitutionsMember" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_ThreeBrazilianFinancialInstitutionsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BorrowingsByNameMember" xlink:label="ifrs-full_BorrowingsByNameMember_1" xlink:title="ifrs-full_BorrowingsByNameMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_BorrowingsByNameAxis" xlink:to="ifrs-full_BorrowingsByNameMember_1" xlink:title="Definition : ifrs-full_BorrowingsByNameAxis to ifrs-full_BorrowingsByNameMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CategoriesOfFinancialAssetsAxis" xlink:label="ifrs-full_CategoriesOfFinancialAssetsAxis" xlink:title="ifrs-full_CategoriesOfFinancialAssetsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfFinancialResourcesTable" xlink:to="ifrs-full_CategoriesOfFinancialAssetsAxis" xlink:title="Definition : csan_DisclosureOfFinancialResourcesTable to ifrs-full_CategoriesOfFinancialAssetsAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_FinancialAssetsCategoryMember" xlink:label="ifrs-full_FinancialAssetsCategoryMember" xlink:title="ifrs-full_FinancialAssetsCategoryMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CategoriesOfFinancialAssetsAxis" xlink:to="ifrs-full_FinancialAssetsCategoryMember" xlink:title="Definition : ifrs-full_CategoriesOfFinancialAssetsAxis to ifrs-full_FinancialAssetsCategoryMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_FinancialAssetsAtAmortisedCostCategoryMember" xlink:label="ifrs-full_FinancialAssetsAtAmortisedCostCategoryMember" xlink:title="ifrs-full_FinancialAssetsAtAmortisedCostCategoryMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_FinancialAssetsCategoryMember" xlink:to="ifrs-full_FinancialAssetsAtAmortisedCostCategoryMember" xlink:title="Definition : ifrs-full_FinancialAssetsCategoryMember to ifrs-full_FinancialAssetsAtAmortisedCostCategoryMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember" xlink:label="ifrs-full_FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember" xlink:title="ifrs-full_FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_FinancialAssetsCategoryMember" xlink:to="ifrs-full_FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember" xlink:title="Definition : ifrs-full_FinancialAssetsCategoryMember to ifrs-full_FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_FinancialAssetsCategoryMember" xlink:label="ifrs-full_FinancialAssetsCategoryMember_1" xlink:title="ifrs-full_FinancialAssetsCategoryMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_CategoriesOfFinancialAssetsAxis" xlink:to="ifrs-full_FinancialAssetsCategoryMember_1" xlink:title="Definition : ifrs-full_CategoriesOfFinancialAssetsAxis to ifrs-full_FinancialAssetsCategoryMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfFinancialInstrumentsAxis" xlink:label="ifrs-full_ClassesOfFinancialInstrumentsAxis" xlink:title="ifrs-full_ClassesOfFinancialInstrumentsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfFinancialResourcesTable" xlink:to="ifrs-full_ClassesOfFinancialInstrumentsAxis" xlink:title="Definition : csan_DisclosureOfFinancialResourcesTable to ifrs-full_ClassesOfFinancialInstrumentsAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfFinancialInstrumentsMember" xlink:label="ifrs-full_ClassesOfFinancialInstrumentsMember" xlink:title="ifrs-full_ClassesOfFinancialInstrumentsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfFinancialInstrumentsAxis" xlink:to="ifrs-full_ClassesOfFinancialInstrumentsMember" xlink:title="Definition : ifrs-full_ClassesOfFinancialInstrumentsAxis to ifrs-full_ClassesOfFinancialInstrumentsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_MarketableSecuritiesMember" xlink:label="csan_MarketableSecuritiesMember" xlink:title="csan_MarketableSecuritiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfFinancialInstrumentsMember" xlink:to="csan_MarketableSecuritiesMember" xlink:title="Definition : ifrs-full_ClassesOfFinancialInstrumentsMember to csan_MarketableSecuritiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RestrictedCashMember" xlink:label="csan_RestrictedCashMember" xlink:title="csan_RestrictedCashMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfFinancialInstrumentsMember" xlink:to="csan_RestrictedCashMember" xlink:title="Definition : ifrs-full_ClassesOfFinancialInstrumentsMember to csan_RestrictedCashMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfFinancialInstrumentsMember" xlink:label="ifrs-full_ClassesOfFinancialInstrumentsMember_1" xlink:title="ifrs-full_ClassesOfFinancialInstrumentsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfFinancialInstrumentsAxis" xlink:to="ifrs-full_ClassesOfFinancialInstrumentsMember_1" xlink:title="Definition : ifrs-full_ClassesOfFinancialInstrumentsAxis to ifrs-full_ClassesOfFinancialInstrumentsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CounterpartiesAxis" xlink:label="ifrs-full_CounterpartiesAxis" xlink:title="ifrs-full_CounterpartiesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfFinancialResourcesTable" xlink:to="ifrs-full_CounterpartiesAxis" xlink:title="Definition : csan_DisclosureOfFinancialResourcesTable to ifrs-full_CounterpartiesAxis" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CounterpartiesMember" xlink:label="ifrs-full_CounterpartiesMember" xlink:title="ifrs-full_CounterpartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CounterpartiesAxis" xlink:to="ifrs-full_CounterpartiesMember" xlink:title="Definition : ifrs-full_CounterpartiesAxis to ifrs-full_CounterpartiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BraziliansourcedNaturalGasMember" xlink:label="csan_BraziliansourcedNaturalGasMember" xlink:title="csan_BraziliansourcedNaturalGasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_CounterpartiesMember" xlink:to="csan_BraziliansourcedNaturalGasMember" xlink:title="Definition : ifrs-full_CounterpartiesMember to csan_BraziliansourcedNaturalGasMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CounterpartiesMember" xlink:label="ifrs-full_CounterpartiesMember_1" xlink:title="ifrs-full_CounterpartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_CounterpartiesAxis" xlink:to="ifrs-full_CounterpartiesMember_1" xlink:title="Definition : ifrs-full_CounterpartiesAxis to ifrs-full_CounterpartiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_FinancialCommitmentsAxis" xlink:label="csan_FinancialCommitmentsAxis" xlink:title="csan_FinancialCommitmentsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfFinancialResourcesTable" xlink:to="csan_FinancialCommitmentsAxis" xlink:title="Definition : csan_DisclosureOfFinancialResourcesTable to csan_FinancialCommitmentsAxis" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_FinancialCommitmentsDomain" xlink:label="csan_FinancialCommitmentsDomain" xlink:title="csan_FinancialCommitmentsDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="csan_FinancialCommitmentsAxis" xlink:to="csan_FinancialCommitmentsDomain" xlink:title="Definition : csan_FinancialCommitmentsAxis to csan_FinancialCommitmentsDomain" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_FEDFUNDSMember" xlink:label="csan_FEDFUNDSMember" xlink:title="csan_FEDFUNDSMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_FinancialCommitmentsDomain" xlink:to="csan_FEDFUNDSMember" xlink:title="Definition : csan_FinancialCommitmentsDomain to csan_FEDFUNDSMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_InterBankDepositCertificateMember" xlink:label="csan_InterBankDepositCertificateMember" xlink:title="csan_InterBankDepositCertificateMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_FinancialCommitmentsDomain" xlink:to="csan_InterBankDepositCertificateMember" xlink:title="Definition : csan_FinancialCommitmentsDomain to csan_InterBankDepositCertificateMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_FinancialCommitmentsDomain" xlink:label="csan_FinancialCommitmentsDomain_1" xlink:title="csan_FinancialCommitmentsDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="csan_FinancialCommitmentsAxis" xlink:to="csan_FinancialCommitmentsDomain_1" xlink:title="Definition : csan_FinancialCommitmentsAxis to csan_FinancialCommitmentsDomain" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_HedgingInstrumentsAxis" xlink:label="ifrs-full_HedgingInstrumentsAxis" xlink:title="ifrs-full_HedgingInstrumentsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfFinancialResourcesTable" xlink:to="ifrs-full_HedgingInstrumentsAxis" xlink:title="Definition : csan_DisclosureOfFinancialResourcesTable to ifrs-full_HedgingInstrumentsAxis" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_HedgingInstrumentsMember" xlink:label="ifrs-full_HedgingInstrumentsMember" xlink:title="ifrs-full_HedgingInstrumentsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_HedgingInstrumentsAxis" xlink:to="ifrs-full_HedgingInstrumentsMember" xlink:title="Definition : ifrs-full_HedgingInstrumentsAxis to ifrs-full_HedgingInstrumentsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_HedgingInstrumentsMember" xlink:label="ifrs-full_HedgingInstrumentsMember_1" xlink:title="ifrs-full_HedgingInstrumentsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_HedgingInstrumentsAxis" xlink:to="ifrs-full_HedgingInstrumentsMember_1" xlink:title="Definition : ifrs-full_HedgingInstrumentsAxis to ifrs-full_HedgingInstrumentsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_MaturityAxis" xlink:label="ifrs-full_MaturityAxis" xlink:title="ifrs-full_MaturityAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfFinancialResourcesTable" xlink:to="ifrs-full_MaturityAxis" xlink:title="Definition : csan_DisclosureOfFinancialResourcesTable to ifrs-full_MaturityAxis" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_AggregatedTimeBandsMember" xlink:label="ifrs-full_AggregatedTimeBandsMember" xlink:title="ifrs-full_AggregatedTimeBandsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_MaturityAxis" xlink:to="ifrs-full_AggregatedTimeBandsMember" xlink:title="Definition : ifrs-full_MaturityAxis to ifrs-full_AggregatedTimeBandsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DecemberTwoThousandTwentyOneMember" xlink:label="csan_DecemberTwoThousandTwentyOneMember" xlink:title="csan_DecemberTwoThousandTwentyOneMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_AggregatedTimeBandsMember" xlink:to="csan_DecemberTwoThousandTwentyOneMember" xlink:title="Definition : ifrs-full_AggregatedTimeBandsMember to csan_DecemberTwoThousandTwentyOneMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_JuneTwoThousandTwentyOneMember" xlink:label="csan_JuneTwoThousandTwentyOneMember" xlink:title="csan_JuneTwoThousandTwentyOneMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_AggregatedTimeBandsMember" xlink:to="csan_JuneTwoThousandTwentyOneMember" xlink:title="Definition : ifrs-full_AggregatedTimeBandsMember to csan_JuneTwoThousandTwentyOneMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_AggregatedTimeBandsMember" xlink:label="ifrs-full_AggregatedTimeBandsMember_1" xlink:title="ifrs-full_AggregatedTimeBandsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_MaturityAxis" xlink:to="ifrs-full_AggregatedTimeBandsMember_1" xlink:title="Definition : ifrs-full_MaturityAxis to ifrs-full_AggregatedTimeBandsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangeAxis" xlink:label="ifrs-full_RangeAxis" xlink:title="ifrs-full_RangeAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfFinancialResourcesTable" xlink:to="ifrs-full_RangeAxis" xlink:title="Definition : csan_DisclosureOfFinancialResourcesTable to ifrs-full_RangeAxis" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember" xlink:title="ifrs-full_RangesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_RangeAxis" xlink:to="ifrs-full_RangesMember" xlink:title="Definition : ifrs-full_RangeAxis to ifrs-full_RangesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BottomOfRangeMember" xlink:label="ifrs-full_BottomOfRangeMember" xlink:title="ifrs-full_BottomOfRangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RangesMember" xlink:to="ifrs-full_BottomOfRangeMember" xlink:title="Definition : ifrs-full_RangesMember to ifrs-full_BottomOfRangeMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TopOfRangeMember" xlink:label="ifrs-full_TopOfRangeMember" xlink:title="ifrs-full_TopOfRangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RangesMember" xlink:to="ifrs-full_TopOfRangeMember" xlink:title="Definition : ifrs-full_RangesMember to ifrs-full_TopOfRangeMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember_1" xlink:title="ifrs-full_RangesMember"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ComgasMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ComgasMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLogisticaSAMember" xlink:label="csan_CosanLogisticaSAMember" xlink:title="csan_CosanLogisticaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanLogisticaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanLogisticaSAMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoSAMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TypesOfInterestRatesAxis" xlink:label="ifrs-full_TypesOfInterestRatesAxis" xlink:title="ifrs-full_TypesOfInterestRatesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfFinancialResourcesTable" xlink:to="ifrs-full_TypesOfInterestRatesAxis" xlink:title="Definition : csan_DisclosureOfFinancialResourcesTable to ifrs-full_TypesOfInterestRatesAxis" xlink:type="arc" use="optional" order="9" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_InterestRateTypesMember" xlink:label="ifrs-full_InterestRateTypesMember" xlink:title="ifrs-full_InterestRateTypesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_TypesOfInterestRatesAxis" xlink:to="ifrs-full_InterestRateTypesMember" xlink:title="Definition : ifrs-full_TypesOfInterestRatesAxis to ifrs-full_InterestRateTypesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CDIIndexMember" xlink:label="csan_CDIIndexMember" xlink:title="csan_CDIIndexMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_CDIIndexMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_CDIIndexMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_TJLPIndexMember" xlink:label="csan_TJLPIndexMember" xlink:title="csan_TJLPIndexMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_TJLPIndexMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_TJLPIndexMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_InterestRateTypesMember" xlink:label="ifrs-full_InterestRateTypesMember_1" xlink:title="ifrs-full_InterestRateTypesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_TypesOfInterestRatesAxis" xlink:to="ifrs-full_InterestRateTypesMember_1" xlink:title="Definition : ifrs-full_TypesOfInterestRatesAxis to ifrs-full_InterestRateTypesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_UnconsolidatedSubsidiariesAxis" xlink:label="ifrs-full_UnconsolidatedSubsidiariesAxis" xlink:title="ifrs-full_UnconsolidatedSubsidiariesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfFinancialResourcesTable" xlink:to="ifrs-full_UnconsolidatedSubsidiariesAxis" xlink:title="Definition : csan_DisclosureOfFinancialResourcesTable to ifrs-full_UnconsolidatedSubsidiariesAxis" xlink:type="arc" use="optional" order="10" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForUnconsolidatedSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForUnconsolidatedSubsidiariesMember" xlink:title="ifrs-full_EntitysTotalForUnconsolidatedSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_UnconsolidatedSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForUnconsolidatedSubsidiariesMember" xlink:title="Definition : ifrs-full_UnconsolidatedSubsidiariesAxis to ifrs-full_EntitysTotalForUnconsolidatedSubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PetrobrasMember" xlink:label="csan_PetrobrasMember" xlink:title="csan_PetrobrasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForUnconsolidatedSubsidiariesMember" xlink:to="csan_PetrobrasMember" xlink:title="Definition : ifrs-full_EntitysTotalForUnconsolidatedSubsidiariesMember to csan_PetrobrasMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForUnconsolidatedSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForUnconsolidatedSubsidiariesMember_1" xlink:title="ifrs-full_EntitysTotalForUnconsolidatedSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_UnconsolidatedSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForUnconsolidatedSubsidiariesMember_1" xlink:title="Definition : ifrs-full_UnconsolidatedSubsidiariesAxis to ifrs-full_EntitysTotalForUnconsolidatedSubsidiariesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_GuaranteeFeeRate" xlink:label="csan_GuaranteeFeeRate" xlink:title="csan_GuaranteeFeeRate"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_HedgedRiskPositonPercentage" xlink:label="csan_HedgedRiskPositonPercentage" xlink:title="csan_HedgedRiskPositonPercentage"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LeaseMaturityTerm1" xlink:label="csan_LeaseMaturityTerm1" xlink:title="csan_LeaseMaturityTerm1"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LineOfCreditFacilityRemainingBorrowingCapacity1" xlink:label="csan_LineOfCreditFacilityRemainingBorrowingCapacity1" xlink:title="csan_LineOfCreditFacilityRemainingBorrowingCapacity1"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_NonVotingPreferredSharesPaidInAmount" xlink:label="csan_NonVotingPreferredSharesPaidInAmount" xlink:title="csan_NonVotingPreferredSharesPaidInAmount"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfFinancialResourcesLineItems" xlink:to="csan_NonVotingPreferredSharesPaidInAmount" xlink:title="Definition : csan_DisclosureOfFinancialResourcesLineItems to csan_NonVotingPreferredSharesPaidInAmount" xlink:type="arc" use="optional" order="12" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PercentageOfOffshoreFinancialInvestmentsRemuneration" xlink:label="csan_PercentageOfOffshoreFinancialInvestmentsRemuneration" xlink:title="csan_PercentageOfOffshoreFinancialInvestmentsRemuneration"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PercentageOfOnshoreFinancialInvestmentsRemuneration" xlink:label="csan_PercentageOfOnshoreFinancialInvestmentsRemuneration" xlink:title="csan_PercentageOfOnshoreFinancialInvestmentsRemuneration"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/FinancialAssetsAndLiabilitiesSummaryOfMarketableSecuritiesDetail">
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_MarketableSecuritiesTable" xlink:label="csan_MarketableSecuritiesTable" xlink:title="csan_MarketableSecuritiesTable"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_MarketableSecuritiesTable" xlink:to="ifrs-full_ClassesOfFinancialAssetsAxis" xlink:title="Definition : csan_MarketableSecuritiesTable to ifrs-full_ClassesOfFinancialAssetsAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_FinancialAssetsMember" xlink:label="ifrs-full_FinancialAssetsMember" xlink:title="ifrs-full_FinancialAssetsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfFinancialAssetsAxis" xlink:to="ifrs-full_FinancialAssetsMember" xlink:title="Definition : ifrs-full_ClassesOfFinancialAssetsAxis to ifrs-full_FinancialAssetsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BankCertificateOfDepositsMember" xlink:label="csan_BankCertificateOfDepositsMember" xlink:title="csan_BankCertificateOfDepositsMember"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_GovernmentSecuritiesMember" xlink:label="csan_GovernmentSecuritiesMember" xlink:title="csan_GovernmentSecuritiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_FinancialAssetsMember" xlink:to="csan_GovernmentSecuritiesMember" xlink:title="Definition : ifrs-full_FinancialAssetsMember to csan_GovernmentSecuritiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RepurchaseAgreementsMember" xlink:label="csan_RepurchaseAgreementsMember" xlink:title="csan_RepurchaseAgreementsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_FinancialAssetsMember" xlink:to="csan_RepurchaseAgreementsMember" xlink:title="Definition : ifrs-full_FinancialAssetsMember to csan_RepurchaseAgreementsMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfFinancialAssetsAxis" xlink:to="ifrs-full_FinancialAssetsMember_1" xlink:title="Definition : ifrs-full_ClassesOfFinancialAssetsAxis to ifrs-full_FinancialAssetsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ShorttermDepositsNotClassifiedAsCashEquivalents" xlink:label="ifrs-full_ShorttermDepositsNotClassifiedAsCashEquivalents" xlink:title="ifrs-full_ShorttermDepositsNotClassifiedAsCashEquivalents"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/FinancialAssetsAndLiabilitiesSummaryOfRestrictedCashDetail">
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfRestrictedCashAndCashEquivalentsLineItems" xlink:label="csan_DisclosureOfRestrictedCashAndCashEquivalentsLineItems" xlink:title="csan_DisclosureOfRestrictedCashAndCashEquivalentsLineItems"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfRestrictedCashAndCashEquivalentsTable" xlink:label="csan_DisclosureOfRestrictedCashAndCashEquivalentsTable" xlink:title="csan_DisclosureOfRestrictedCashAndCashEquivalentsTable"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfFinancialAssetsAxis" xlink:label="ifrs-full_ClassesOfFinancialAssetsAxis" xlink:title="ifrs-full_ClassesOfFinancialAssetsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfRestrictedCashAndCashEquivalentsTable" xlink:to="ifrs-full_ClassesOfFinancialAssetsAxis" xlink:title="Definition : csan_DisclosureOfRestrictedCashAndCashEquivalentsTable to ifrs-full_ClassesOfFinancialAssetsAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_FinancialAssetsMember" xlink:label="ifrs-full_FinancialAssetsMember" xlink:title="ifrs-full_FinancialAssetsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfFinancialAssetsAxis" xlink:to="ifrs-full_FinancialAssetsMember" xlink:title="Definition : ifrs-full_ClassesOfFinancialAssetsAxis to ifrs-full_FinancialAssetsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SecuritiesPledgedAsCollateral1Member" xlink:label="csan_SecuritiesPledgedAsCollateral1Member" xlink:title="csan_SecuritiesPledgedAsCollateral1Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_FinancialAssetsMember" xlink:to="csan_SecuritiesPledgedAsCollateral1Member" xlink:title="Definition : ifrs-full_FinancialAssetsMember to csan_SecuritiesPledgedAsCollateral1Member" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfFinancialAssetsAxis" xlink:to="ifrs-full_FinancialAssetsMember_1" xlink:title="Definition : ifrs-full_ClassesOfFinancialAssetsAxis to ifrs-full_FinancialAssetsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RestrictedCashAndCashEquivalents" xlink:label="ifrs-full_RestrictedCashAndCashEquivalents" xlink:title="ifrs-full_RestrictedCashAndCashEquivalents"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfRestrictedCashAndCashEquivalentsLineItems" xlink:to="ifrs-full_RestrictedCashAndCashEquivalents" xlink:title="Definition : csan_DisclosureOfRestrictedCashAndCashEquivalentsLineItems to ifrs-full_RestrictedCashAndCashEquivalents" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfTradeReceivablesTable" xlink:label="csan_DisclosureOfTradeReceivablesTable" xlink:title="csan_DisclosureOfTradeReceivablesTable"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CarryingAmountMember" xlink:label="ifrs-full_CarryingAmountMember" xlink:title="ifrs-full_CarryingAmountMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:to="ifrs-full_CarryingAmountMember" xlink:title="Definition : ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis to ifrs-full_CarryingAmountMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_AccumulatedImpairmentMember" xlink:label="ifrs-full_AccumulatedImpairmentMember" xlink:title="ifrs-full_AccumulatedImpairmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_CarryingAmountMember" xlink:to="ifrs-full_AccumulatedImpairmentMember" xlink:title="Definition : ifrs-full_CarryingAmountMember to ifrs-full_AccumulatedImpairmentMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:label="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="ifrs-full_SignificantInvestmentsInSubsidiariesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfTradeReceivablesTable" xlink:to="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="Definition : csan_DisclosureOfTradeReceivablesTable to ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ComgasMember" xlink:label="csan_ComgasMember" xlink:title="csan_ComgasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ComgasMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ComgasMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfTradeReceivablesLineItems" xlink:to="ifrs-full_ReversalOfImpairmentLossRecognisedInProfitOrLossTradeReceivables" xlink:title="Definition : csan_DisclosureOfTradeReceivablesLineItems to ifrs-full_ReversalOfImpairmentLossRecognisedInProfitOrLossTradeReceivables" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/FinancialAssetsAndLiabilitiesSummaryOfAgeingOfTradeReceivablesDetail">
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfTradeReceivablesTable" xlink:label="csan_DisclosureOfTradeReceivablesTable" xlink:title="csan_DisclosureOfTradeReceivablesTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="csan_DisclosureOfTradeReceivablesLineItems" xlink:to="csan_DisclosureOfTradeReceivablesTable" xlink:title="Definition : csan_DisclosureOfTradeReceivablesLineItems to csan_DisclosureOfTradeReceivablesTable" xlink:type="arc" use="optional" order="0" xbrldt:closed="true" xbrldt:contextElement="segment"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:to="ifrs-full_CarryingAmountMember" xlink:title="Definition : ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis to ifrs-full_CarryingAmountMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_CarryingAmountMember" xlink:to="ifrs-full_AccumulatedImpairmentMember" xlink:title="Definition : ifrs-full_CarryingAmountMember to ifrs-full_AccumulatedImpairmentMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CarryingAmountMember" xlink:label="ifrs-full_CarryingAmountMember_1" xlink:title="ifrs-full_CarryingAmountMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:to="ifrs-full_CarryingAmountMember_1" xlink:title="Definition : ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis to ifrs-full_CarryingAmountMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfTradeReceivablesTable" xlink:to="ifrs-full_MaturityAxis" xlink:title="Definition : csan_DisclosureOfTradeReceivablesTable to ifrs-full_MaturityAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_AggregatedTimeBandsMember" xlink:label="ifrs-full_AggregatedTimeBandsMember" xlink:title="ifrs-full_AggregatedTimeBandsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_MaturityAxis" xlink:to="ifrs-full_AggregatedTimeBandsMember" xlink:title="Definition : ifrs-full_MaturityAxis to ifrs-full_AggregatedTimeBandsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_MoreThanNinetyDaysMember" xlink:label="csan_MoreThanNinetyDaysMember" xlink:title="csan_MoreThanNinetyDaysMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_AggregatedTimeBandsMember" xlink:to="csan_MoreThanNinetyDaysMember" xlink:title="Definition : ifrs-full_AggregatedTimeBandsMember to csan_MoreThanNinetyDaysMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_NotDueMember" xlink:label="csan_NotDueMember" xlink:title="csan_NotDueMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_AggregatedTimeBandsMember" xlink:to="csan_NotDueMember" xlink:title="Definition : ifrs-full_AggregatedTimeBandsMember to csan_NotDueMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OverdueOneToThirtyDaysMember" xlink:label="csan_OverdueOneToThirtyDaysMember" xlink:title="csan_OverdueOneToThirtyDaysMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_AggregatedTimeBandsMember" xlink:to="csan_OverdueOneToThirtyDaysMember" xlink:title="Definition : ifrs-full_AggregatedTimeBandsMember to csan_OverdueOneToThirtyDaysMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OverdueSixtyOneToNinetyDaysMember" xlink:label="csan_OverdueSixtyOneToNinetyDaysMember" xlink:title="csan_OverdueSixtyOneToNinetyDaysMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_AggregatedTimeBandsMember" xlink:to="csan_OverdueSixtyOneToNinetyDaysMember" xlink:title="Definition : ifrs-full_AggregatedTimeBandsMember to csan_OverdueSixtyOneToNinetyDaysMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OverdueThirtyOneToSixtyDaysMember" xlink:label="csan_OverdueThirtyOneToSixtyDaysMember" xlink:title="csan_OverdueThirtyOneToSixtyDaysMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_AggregatedTimeBandsMember" xlink:to="csan_OverdueThirtyOneToSixtyDaysMember" xlink:title="Definition : ifrs-full_AggregatedTimeBandsMember to csan_OverdueThirtyOneToSixtyDaysMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_AggregatedTimeBandsMember" xlink:label="ifrs-full_AggregatedTimeBandsMember_1" xlink:title="ifrs-full_AggregatedTimeBandsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_MaturityAxis" xlink:to="ifrs-full_AggregatedTimeBandsMember_1" xlink:title="Definition : ifrs-full_MaturityAxis to ifrs-full_AggregatedTimeBandsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfTradeReceivablesLineItems" xlink:to="ifrs-full_TradeReceivables" xlink:title="Definition : csan_DisclosureOfTradeReceivablesLineItems to ifrs-full_TradeReceivables" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/FinancialAssetsAndLiabilitiesSummaryOfReceivablesFromAndPayablesToRelatedPartiesDetail">
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfReceivablesAndPayablesTable" xlink:label="csan_DisclosureOfReceivablesAndPayablesTable" xlink:title="csan_DisclosureOfReceivablesAndPayablesTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="csan_DisclosureOfReceivablesAndPayablesLineItems" xlink:to="csan_DisclosureOfReceivablesAndPayablesTable" xlink:title="Definition : csan_DisclosureOfReceivablesAndPayablesLineItems to csan_DisclosureOfReceivablesAndPayablesTable" xlink:type="arc" use="optional" order="0" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:label="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:title="ifrs-full_CategoriesOfRelatedPartiesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfReceivablesAndPayablesTable" xlink:to="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:title="Definition : csan_DisclosureOfReceivablesAndPayablesTable to ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:label="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:title="ifrs-full_EntitysTotalForRelatedPartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:to="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:title="Definition : ifrs-full_CategoriesOfRelatedPartiesAxis to ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AguassantaParticipacoesSAMember" xlink:label="csan_AguassantaParticipacoesSAMember" xlink:title="csan_AguassantaParticipacoesSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_AguassantaParticipacoesSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_AguassantaParticipacoesSAMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_JanusBrasilParticipacoesSAMember" xlink:label="csan_JanusBrasilParticipacoesSAMember" xlink:title="csan_JanusBrasilParticipacoesSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_JanusBrasilParticipacoesSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_JanusBrasilParticipacoesSAMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_OtherRelatedPartiesMember" xlink:label="ifrs-full_OtherRelatedPartiesMember" xlink:title="ifrs-full_OtherRelatedPartiesMember"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:to="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:title="Definition : ifrs-full_CategoriesOfRelatedPartiesAxis to ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_AguassantaInvestimentosSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_AguassantaInvestimentosSAMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:title="dei_EntityDomain"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="csan_CosanSAMember" xlink:title="Definition : dei_EntityDomain to csan_CosanSAMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RaizenInternationalUniversalCorporationMember" xlink:label="csan_RaizenInternationalUniversalCorporationMember" xlink:title="csan_RaizenInternationalUniversalCorporationMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_RaizenInternationalUniversalCorporationMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_RaizenInternationalUniversalCorporationMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="ifrs-full_OtherRelatedPartiesMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to ifrs-full_OtherRelatedPartiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RaizenEnergiaMember" xlink:label="csan_RaizenEnergiaMember" xlink:title="csan_RaizenEnergiaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_RaizenEnergiaMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_RaizenEnergiaMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_UsinaSantaLuizaMember" xlink:label="csan_UsinaSantaLuizaMember" xlink:title="csan_UsinaSantaLuizaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_UsinaSantaLuizaMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_UsinaSantaLuizaMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PurchaseOfGoodsMember" xlink:label="csan_PurchaseOfGoodsMember" xlink:title="csan_PurchaseOfGoodsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_PurchaseOfGoodsMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_PurchaseOfGoodsMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RaizenCombustiveisSAMember" xlink:label="csan_RaizenCombustiveisSAMember" xlink:title="csan_RaizenCombustiveisSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_RaizenCombustiveisSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_RaizenCombustiveisSAMember" xlink:type="arc" order="5" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfReceivablesAndPayablesLineItems" xlink:to="ifrs-full_PurchasesOfGoodsRelatedPartyTransactions" xlink:title="Definition : csan_DisclosureOfReceivablesAndPayablesLineItems to ifrs-full_PurchasesOfGoodsRelatedPartyTransactions" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LoansAndBorrowings" xlink:label="csan_LoansAndBorrowings" xlink:title="csan_LoansAndBorrowings"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems" xlink:to="csan_LoansAndBorrowings" xlink:title="Definition : ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems to csan_LoansAndBorrowings" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DescriptionOfBorrowingsObjective" xlink:label="csan_DescriptionOfBorrowingsObjective" xlink:title="csan_DescriptionOfBorrowingsObjective"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_TypesOfFinancialLiabilitiesAxis" xlink:to="ifrs-full_FinancialLiabilitiesTypeMember" xlink:title="Definition : ifrs-full_TypesOfFinancialLiabilitiesAxis to ifrs-full_FinancialLiabilitiesTypeMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_FinancialLiabilitiesTypeMember" xlink:to="csan_SecuredBorrowingsMember" xlink:title="Definition : ifrs-full_FinancialLiabilitiesTypeMember to csan_SecuredBorrowingsMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_FinancialLiabilitiesTypeMember" xlink:label="ifrs-full_FinancialLiabilitiesTypeMember_1" xlink:title="ifrs-full_FinancialLiabilitiesTypeMember"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BorrowingsByNameAxis" xlink:label="ifrs-full_BorrowingsByNameAxis" xlink:title="ifrs-full_BorrowingsByNameAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable" xlink:to="ifrs-full_BorrowingsByNameAxis" xlink:title="Definition : ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable to ifrs-full_BorrowingsByNameAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BrazilianNationalEconomicandSocialDevelopmentBankMember" xlink:label="csan_BrazilianNationalEconomicandSocialDevelopmentBankMember" xlink:title="csan_BrazilianNationalEconomicandSocialDevelopmentBankMember"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ExportCreditAgreementMember" xlink:label="csan_ExportCreditAgreementMember" xlink:title="csan_ExportCreditAgreementMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_ExportCreditAgreementMember" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_ExportCreditAgreementMember" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_EuropeanInvestmentBankMember" xlink:label="csan_EuropeanInvestmentBankMember" xlink:title="csan_EuropeanInvestmentBankMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_EuropeanInvestmentBankMember" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_EuropeanInvestmentBankMember" xlink:type="arc" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ForeignLoansMember" xlink:label="csan_ForeignLoansMember" xlink:title="csan_ForeignLoansMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_ForeignLoansMember" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_ForeignLoansMember" xlink:type="arc" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ExportCreditNoteMember" xlink:label="csan_ExportCreditNoteMember" xlink:title="csan_ExportCreditNoteMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_ExportCreditNoteMember" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_ExportCreditNoteMember" xlink:type="arc" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_Resolution4131Member" xlink:label="csan_Resolution4131Member" xlink:title="csan_Resolution4131Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_Resolution4131Member" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_Resolution4131Member" xlink:type="arc" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BankingCreditCertificatesMember" xlink:label="csan_BankingCreditCertificatesMember" xlink:title="csan_BankingCreditCertificatesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_BankingCreditCertificatesMember" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_BankingCreditCertificatesMember" xlink:type="arc" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PerpetualNotesMember" xlink:label="csan_PerpetualNotesMember" xlink:title="csan_PerpetualNotesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_PerpetualNotesMember" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_PerpetualNotesMember" xlink:type="arc" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SeniorNotesDue2023Member" xlink:label="csan_SeniorNotesDue2023Member" xlink:title="csan_SeniorNotesDue2023Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_SeniorNotesDue2023Member" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_SeniorNotesDue2023Member" xlink:type="arc" order="8" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SeniorNotesDue2024Member" xlink:label="csan_SeniorNotesDue2024Member" xlink:title="csan_SeniorNotesDue2024Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_SeniorNotesDue2024Member" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_SeniorNotesDue2024Member" xlink:type="arc" order="9" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SeniorNotesDue2025Member" xlink:label="csan_SeniorNotesDue2025Member" xlink:title="csan_SeniorNotesDue2025Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_SeniorNotesDue2025Member" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_SeniorNotesDue2025Member" xlink:type="arc" order="10" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SeniorNotesDue2027Member" xlink:label="csan_SeniorNotesDue2027Member" xlink:title="csan_SeniorNotesDue2027Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_SeniorNotesDue2027Member" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_SeniorNotesDue2027Member" xlink:type="arc" order="11" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SeniorNotesDue2028Member" xlink:label="csan_SeniorNotesDue2028Member" xlink:title="csan_SeniorNotesDue2028Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_SeniorNotesDue2028Member" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_SeniorNotesDue2028Member" xlink:type="arc" order="12" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PrepaymentMember" xlink:label="csan_PrepaymentMember" xlink:title="csan_PrepaymentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_PrepaymentMember" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_PrepaymentMember" xlink:type="arc" order="13" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BankOverdraftMember" xlink:label="csan_BankOverdraftMember" xlink:title="csan_BankOverdraftMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_BankOverdraftMember" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_BankOverdraftMember" xlink:type="arc" order="14" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DebenturesMember" xlink:label="csan_DebenturesMember" xlink:title="csan_DebenturesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_DebenturesMember" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_DebenturesMember" xlink:type="arc" order="15" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_WorkingCapitalMember" xlink:label="csan_WorkingCapitalMember" xlink:title="csan_WorkingCapitalMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_WorkingCapitalMember" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_WorkingCapitalMember" xlink:type="arc" order="16" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PromissoryNotesMember" xlink:label="csan_PromissoryNotesMember" xlink:title="csan_PromissoryNotesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_PromissoryNotesMember" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_PromissoryNotesMember" xlink:type="arc" order="17" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SeniorNotesDue2029Member" xlink:label="csan_SeniorNotesDue2029Member" xlink:title="csan_SeniorNotesDue2029Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_SeniorNotesDue2029Member" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_SeniorNotesDue2029Member" xlink:type="arc" order="18" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_BorrowingsByNameAxis" xlink:to="ifrs-full_BorrowingsByNameMember_1" xlink:title="Definition : ifrs-full_BorrowingsByNameAxis to ifrs-full_BorrowingsByNameMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable" xlink:to="ifrs-full_TypesOfInterestRatesAxis" xlink:title="Definition : ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable to ifrs-full_TypesOfInterestRatesAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_InterestRateTypesMember" xlink:label="ifrs-full_InterestRateTypesMember" xlink:title="ifrs-full_InterestRateTypesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_TypesOfInterestRatesAxis" xlink:to="ifrs-full_InterestRateTypesMember" xlink:title="Definition : ifrs-full_TypesOfInterestRatesAxis to ifrs-full_InterestRateTypesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_TJLPIndexMember" xlink:label="csan_TJLPIndexMember" xlink:title="csan_TJLPIndexMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_TJLPIndexMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_TJLPIndexMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_URTJLPIndexMember" xlink:label="csan_URTJLPIndexMember" xlink:title="csan_URTJLPIndexMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_URTJLPIndexMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_URTJLPIndexMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_FixedInterestRateMember" xlink:label="ifrs-full_FixedInterestRateMember" xlink:title="ifrs-full_FixedInterestRateMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="ifrs-full_FixedInterestRateMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to ifrs-full_FixedInterestRateMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IndexTJ462Plus1Point80PercentMember" xlink:label="csan_IndexTJ462Plus1Point80PercentMember" xlink:title="csan_IndexTJ462Plus1Point80PercentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_IndexTJ462Plus1Point80PercentMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_IndexTJ462Plus1Point80PercentMember" xlink:type="arc" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SelicIndexPlus1Point80PercentMember" xlink:label="csan_SelicIndexPlus1Point80PercentMember" xlink:title="csan_SelicIndexPlus1Point80PercentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_SelicIndexPlus1Point80PercentMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_SelicIndexPlus1Point80PercentMember" xlink:type="arc" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SelicIndexMember" xlink:label="csan_SelicIndexMember" xlink:title="csan_SelicIndexMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_SelicIndexMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_SelicIndexMember" xlink:type="arc" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SelicIndexPlus1Point96PercentMember" xlink:label="csan_SelicIndexPlus1Point96PercentMember" xlink:title="csan_SelicIndexPlus1Point96PercentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_SelicIndexPlus1Point96PercentMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_SelicIndexPlus1Point96PercentMember" xlink:type="arc" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IPCAIndexMember" xlink:label="csan_IPCAIndexMember" xlink:title="csan_IPCAIndexMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_IPCAIndexMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_IPCAIndexMember" xlink:type="arc" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IPCAIndexPlus3Point25PercentMember" xlink:label="csan_IPCAIndexPlus3Point25PercentMember" xlink:title="csan_IPCAIndexPlus3Point25PercentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_IPCAIndexPlus3Point25PercentMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_IPCAIndexPlus3Point25PercentMember" xlink:type="arc" order="8" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IPCAIndexPlus4Point10PercentMember" xlink:label="csan_IPCAIndexPlus4Point10PercentMember" xlink:title="csan_IPCAIndexPlus4Point10PercentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_IPCAIndexPlus4Point10PercentMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_IPCAIndexPlus4Point10PercentMember" xlink:type="arc" order="9" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_EuriborIndexPlus0Point58PercentMember" xlink:label="csan_EuriborIndexPlus0Point58PercentMember" xlink:title="csan_EuriborIndexPlus0Point58PercentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_EuriborIndexPlus0Point58PercentMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_EuriborIndexPlus0Point58PercentMember" xlink:type="arc" order="10" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_USDollarIndexPlus3Point88PercentMember" xlink:label="csan_USDollarIndexPlus3Point88PercentMember" xlink:title="csan_USDollarIndexPlus3Point88PercentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_USDollarIndexPlus3Point88PercentMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_USDollarIndexPlus3Point88PercentMember" xlink:type="arc" order="11" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_USDollarIndexPlus2Point94PercentMember" xlink:label="csan_USDollarIndexPlus2Point94PercentMember" xlink:title="csan_USDollarIndexPlus2Point94PercentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_USDollarIndexPlus2Point94PercentMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_USDollarIndexPlus2Point94PercentMember" xlink:type="arc" order="12" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_USDollarIndexPlusLibor6MonthPlus0Point54PercentMember" xlink:label="csan_USDollarIndexPlusLibor6MonthPlus0Point54PercentMember" xlink:title="csan_USDollarIndexPlusLibor6MonthPlus0Point54PercentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_USDollarIndexPlusLibor6MonthPlus0Point54PercentMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_USDollarIndexPlusLibor6MonthPlus0Point54PercentMember" xlink:type="arc" order="13" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_USDollarIndexPlusLibor6MonthPlus0Point61PercentMember" xlink:label="csan_USDollarIndexPlusLibor6MonthPlus0Point61PercentMember" xlink:title="csan_USDollarIndexPlusLibor6MonthPlus0Point61PercentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_USDollarIndexPlusLibor6MonthPlus0Point61PercentMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_USDollarIndexPlusLibor6MonthPlus0Point61PercentMember" xlink:type="arc" order="14" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_GBPIndexPlusLibor6MonthPlus1Point50PercentMember" xlink:label="csan_GBPIndexPlusLibor6MonthPlus1Point50PercentMember" xlink:title="csan_GBPIndexPlusLibor6MonthPlus1Point50PercentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_GBPIndexPlusLibor6MonthPlus1Point50PercentMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_GBPIndexPlusLibor6MonthPlus1Point50PercentMember" xlink:type="arc" order="15" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_GBPIndexFixedInterestRateMember" xlink:label="csan_GBPIndexFixedInterestRateMember" xlink:title="csan_GBPIndexFixedInterestRateMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_GBPIndexFixedInterestRateMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_GBPIndexFixedInterestRateMember" xlink:type="arc" order="16" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_GBPIndexPlusLibor6MonthPlus1Point10PercentMember" xlink:label="csan_GBPIndexPlusLibor6MonthPlus1Point10PercentMember" xlink:title="csan_GBPIndexPlusLibor6MonthPlus1Point10PercentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_GBPIndexPlusLibor6MonthPlus1Point10PercentMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_GBPIndexPlusLibor6MonthPlus1Point10PercentMember" xlink:type="arc" order="17" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_EUROIndexFixedInterestRateMember" xlink:label="csan_EUROIndexFixedInterestRateMember" xlink:title="csan_EUROIndexFixedInterestRateMember"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ComgasMember" xlink:label="csan_ComgasMember" xlink:title="csan_ComgasMember"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:label="ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:title="ifrs-full_EntitysTotalForBusinessCombinationsMember"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:to="csan_CosanSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForBusinessCombinationsMember to csan_CosanSAMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:to="csan_CosanLimitedMember" xlink:title="Definition : ifrs-full_EntitysTotalForBusinessCombinationsMember to csan_CosanLimitedMember" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:label="ifrs-full_EntitysTotalForBusinessCombinationsMember_1" xlink:title="ifrs-full_EntitysTotalForBusinessCombinationsMember"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_LiabilitiesArisingFromFinancingActivitiesMember" xlink:label="ifrs-full_LiabilitiesArisingFromFinancingActivitiesMember" xlink:title="ifrs-full_LiabilitiesArisingFromFinancingActivitiesMember"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_LiabilitiesArisingFromFinancingActivitiesMember" xlink:to="csan_FinanceLeaseMember" xlink:title="Definition : ifrs-full_LiabilitiesArisingFromFinancingActivitiesMember to csan_FinanceLeaseMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_LiabilitiesArisingFromFinancingActivitiesMember" xlink:label="ifrs-full_LiabilitiesArisingFromFinancingActivitiesMember_1" xlink:title="ifrs-full_LiabilitiesArisingFromFinancingActivitiesMember"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OperatingLeaseLiability" xlink:label="csan_OperatingLeaseLiability" xlink:title="csan_OperatingLeaseLiability"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_InitialRecognitionOfIfrs16" xlink:label="csan_InitialRecognitionOfIfrs16" xlink:title="csan_InitialRecognitionOfIfrs16"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfMovementOfLeasesLineItems" xlink:to="ifrs-full_AdditionsToRightofuseAssets" xlink:title="Definition : csan_DisclosureOfMovementOfLeasesLineItems to ifrs-full_AdditionsToRightofuseAssets" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_TransferOfLiabilities" xlink:label="csan_TransferOfLiabilities" xlink:title="csan_TransferOfLiabilities"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ContractsMonetaryCorrection" xlink:label="csan_ContractsMonetaryCorrection" xlink:title="csan_ContractsMonetaryCorrection"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PaymentOfLeasePrincipal" xlink:label="csan_PaymentOfLeasePrincipal" xlink:title="csan_PaymentOfLeasePrincipal"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PaymentOfLeaseInterest" xlink:label="csan_PaymentOfLeaseInterest" xlink:title="csan_PaymentOfLeaseInterest"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfMovementOfLeasesLineItems" xlink:to="csan_PaymentOfLeaseInterest" xlink:title="Definition : csan_DisclosureOfMovementOfLeasesLineItems to csan_PaymentOfLeaseInterest" xlink:type="arc" use="optional" order="11" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/FinancialAssetsAndLiabilitiesSummaryOfLeaseExpenseDetail">
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/FinancialAssetsAndLiabilitiesSummaryOfTradePayablesDetail">
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfTradeAndOtherPayablesLineItems" xlink:label="csan_DisclosureOfTradeAndOtherPayablesLineItems" xlink:title="csan_DisclosureOfTradeAndOtherPayablesLineItems"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_CounterpartiesMember" xlink:to="csan_MaterialsAndServiceSuppliersMember" xlink:title="Definition : ifrs-full_CounterpartiesMember to csan_MaterialsAndServiceSuppliersMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_FuelAndLubricantsSuppliersMember" xlink:label="csan_FuelAndLubricantsSuppliersMember" xlink:title="csan_FuelAndLubricantsSuppliersMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_CounterpartiesMember" xlink:to="csan_FuelAndLubricantsSuppliersMember" xlink:title="Definition : ifrs-full_CounterpartiesMember to csan_FuelAndLubricantsSuppliersMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfFinancialInstrumentsLineItems" xlink:to="csan_DerivativeFinancialInstruments" xlink:title="Definition : ifrs-full_DisclosureOfFinancialInstrumentsLineItems to csan_DerivativeFinancialInstruments" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfFinancialInstrumentsLineItems" xlink:to="ifrs-full_DerivativeFinancialAssets" xlink:title="Definition : ifrs-full_DisclosureOfFinancialInstrumentsLineItems to ifrs-full_DerivativeFinancialAssets" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DerivativeFinancialLiabilities" xlink:label="ifrs-full_DerivativeFinancialLiabilities" xlink:title="ifrs-full_DerivativeFinancialLiabilities"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfFinancialInstrumentsLineItems" xlink:to="ifrs-full_DerivativeFinancialLiabilities" xlink:title="Definition : ifrs-full_DisclosureOfFinancialInstrumentsLineItems to ifrs-full_DerivativeFinancialLiabilities" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfFinancialInstrumentsLineItems" xlink:to="ifrs-full_NotionalAmount" xlink:title="Definition : ifrs-full_DisclosureOfFinancialInstrumentsLineItems to ifrs-full_NotionalAmount" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfFinancialInstrumentsLineItems" xlink:to="csan_FairValueOfDerivativeFinancialAssetsLiability" xlink:title="Definition : ifrs-full_DisclosureOfFinancialInstrumentsLineItems to csan_FairValueOfDerivativeFinancialAssetsLiability" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_HedgedItemsAxis" xlink:to="ifrs-full_HedgedItemsMember" xlink:title="Definition : ifrs-full_HedgedItemsAxis to ifrs-full_HedgedItemsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ExchangeRateDerivativesMember" xlink:label="csan_ExchangeRateDerivativesMember" xlink:title="csan_ExchangeRateDerivativesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_HedgedItemsMember" xlink:to="csan_ExchangeRateDerivativesMember" xlink:title="Definition : ifrs-full_HedgedItemsMember to csan_ExchangeRateDerivativesMember" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_InterestRateAndExchangeRateRiskMember" xlink:label="csan_InterestRateAndExchangeRateRiskMember" xlink:title="csan_InterestRateAndExchangeRateRiskMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_HedgedItemsMember" xlink:to="csan_InterestRateAndExchangeRateRiskMember" xlink:title="Definition : ifrs-full_HedgedItemsMember to csan_InterestRateAndExchangeRateRiskMember" xlink:type="arc" order="2" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_HedgedItemsAxis" xlink:to="ifrs-full_HedgedItemsMember_1" xlink:title="Definition : ifrs-full_HedgedItemsAxis to ifrs-full_HedgedItemsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfFinancialAssetsAxis" xlink:to="ifrs-full_FinancialAssetsMember" xlink:title="Definition : ifrs-full_ClassesOfFinancialAssetsAxis to ifrs-full_FinancialAssetsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_FinancialAssetsMember" xlink:to="ifrs-full_ForwardContractMember" xlink:title="Definition : ifrs-full_FinancialAssetsMember to ifrs-full_ForwardContractMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_FinancialAssetsMember" xlink:to="csan_CommodityForwardContractMember" xlink:title="Definition : ifrs-full_FinancialAssetsMember to csan_CommodityForwardContractMember" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SwapContractForSharesMember" xlink:label="csan_SwapContractForSharesMember" xlink:title="csan_SwapContractForSharesMember"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_FinancialAssetsMember" xlink:to="csan_InflationAndInterestRateSwapContractMember" xlink:title="Definition : ifrs-full_FinancialAssetsMember to csan_InflationAndInterestRateSwapContractMember" xlink:type="arc" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_InterestRateSwapContractMember" xlink:label="ifrs-full_InterestRateSwapContractMember" xlink:title="ifrs-full_InterestRateSwapContractMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_FinancialAssetsMember" xlink:to="ifrs-full_InterestRateSwapContractMember" xlink:title="Definition : ifrs-full_FinancialAssetsMember to ifrs-full_InterestRateSwapContractMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_FinancialAssetsMember" xlink:to="csan_ExchangeAndInterestRateSwapContractMember" xlink:title="Definition : ifrs-full_FinancialAssetsMember to csan_ExchangeAndInterestRateSwapContractMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_AggregatedMeasurementMember" xlink:to="ifrs-full_AtFairValueMember" xlink:title="Definition : ifrs-full_AggregatedMeasurementMember to ifrs-full_AtFairValueMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_MeasurementAxis" xlink:to="ifrs-full_AggregatedMeasurementMember_1" xlink:title="Definition : ifrs-full_MeasurementAxis to ifrs-full_AggregatedMeasurementMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsMember" xlink:label="ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsMember_1" xlink:title="ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis" xlink:to="ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsMember_1" xlink:title="Definition : ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis to ifrs-full_TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_TradeAndOtherCurrentReceivablesLineItems" xlink:label="csan_TradeAndOtherCurrentReceivablesLineItems" xlink:title="csan_TradeAndOtherCurrentReceivablesLineItems"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IncomeGrantFromJudicialPrecedent" xlink:label="csan_IncomeGrantFromJudicialPrecedent" xlink:title="csan_IncomeGrantFromJudicialPrecedent"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_TradeAndOtherCurrentReceivablesLineItems" xlink:to="csan_IncomeGrantFromJudicialPrecedent" xlink:title="Definition : csan_TradeAndOtherCurrentReceivablesLineItems to csan_IncomeGrantFromJudicialPrecedent" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_TradeAndOtherCurrentReceivablesTable" xlink:label="csan_TradeAndOtherCurrentReceivablesTable" xlink:title="csan_TradeAndOtherCurrentReceivablesTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="csan_TradeAndOtherCurrentReceivablesLineItems" xlink:to="csan_TradeAndOtherCurrentReceivablesTable" xlink:title="Definition : csan_TradeAndOtherCurrentReceivablesLineItems to csan_TradeAndOtherCurrentReceivablesTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_LitigationCaseAxis" xlink:label="srt_LitigationCaseAxis" xlink:title="srt_LitigationCaseAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_TradeAndOtherCurrentReceivablesTable" xlink:to="srt_LitigationCaseAxis" xlink:title="Definition : csan_TradeAndOtherCurrentReceivablesTable to srt_LitigationCaseAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_LitigationCaseTypeDomain" xlink:label="srt_LitigationCaseTypeDomain" xlink:title="srt_LitigationCaseTypeDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_LitigationCaseAxis" xlink:to="srt_LitigationCaseTypeDomain" xlink:title="Definition : srt_LitigationCaseAxis to srt_LitigationCaseTypeDomain" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_FederalSupremeCourtMember" xlink:label="csan_FederalSupremeCourtMember" xlink:title="csan_FederalSupremeCourtMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_LitigationCaseTypeDomain" xlink:to="csan_FederalSupremeCourtMember" xlink:title="Definition : srt_LitigationCaseTypeDomain to csan_FederalSupremeCourtMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_LitigationCaseTypeDomain" xlink:label="srt_LitigationCaseTypeDomain_1" xlink:title="srt_LitigationCaseTypeDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_LitigationCaseAxis" xlink:to="srt_LitigationCaseTypeDomain_1" xlink:title="Definition : srt_LitigationCaseAxis to srt_LitigationCaseTypeDomain" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/InvestmentsInAssociatesSummaryOfInformationInAssociatesOfCompanyAndCompanysOwnershipDetail">
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfAssociatesAndJointVenturesLineItems" xlink:label="csan_DisclosureOfAssociatesAndJointVenturesLineItems" xlink:title="csan_DisclosureOfAssociatesAndJointVenturesLineItems"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable" xlink:label="ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable" xlink:title="ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="csan_DisclosureOfAssociatesAndJointVenturesLineItems" xlink:to="ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable" xlink:title="Definition : csan_DisclosureOfAssociatesAndJointVenturesLineItems to ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable" xlink:type="arc" use="optional" order="0" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:label="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:title="ifrs-full_CategoriesOfRelatedPartiesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable" xlink:to="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:title="Definition : ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable to ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:label="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:title="ifrs-full_EntitysTotalForRelatedPartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:to="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:title="Definition : ifrs-full_CategoriesOfRelatedPartiesAxis to ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_AssociatesMember" xlink:label="ifrs-full_AssociatesMember" xlink:title="ifrs-full_AssociatesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="ifrs-full_AssociatesMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to ifrs-full_AssociatesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:label="ifrs-full_EntitysTotalForRelatedPartiesMember_1" xlink:title="ifrs-full_EntitysTotalForRelatedPartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:to="ifrs-full_EntitysTotalForRelatedPartiesMember_1" xlink:title="Definition : ifrs-full_CategoriesOfRelatedPartiesAxis to ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:title="dei_LegalEntityAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable" xlink:to="dei_LegalEntityAxis" xlink:title="Definition : ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable to dei_LegalEntityAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:title="dei_EntityDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" xlink:title="Definition : dei_LegalEntityAxis to dei_EntityDomain" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLogisticaSAMember" xlink:label="csan_CosanLogisticaSAMember" xlink:title="csan_CosanLogisticaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="csan_CosanLogisticaSAMember" xlink:title="Definition : dei_EntityDomain to csan_CosanLogisticaSAMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanSAMember" xlink:label="csan_CosanSAMember" xlink:title="csan_CosanSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="csan_CosanSAMember" xlink:title="Definition : dei_EntityDomain to csan_CosanSAMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLimitedPartnersBrasilConsultoriaLtdaMember" xlink:label="csan_CosanLimitedPartnersBrasilConsultoriaLtdaMember" xlink:title="csan_CosanLimitedPartnersBrasilConsultoriaLtdaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="csan_CosanLimitedPartnersBrasilConsultoriaLtdaMember" xlink:title="Definition : dei_EntityDomain to csan_CosanLimitedPartnersBrasilConsultoriaLtdaMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SinlogTecnologiaEmLogsticaSaMember" xlink:label="csan_SinlogTecnologiaEmLogsticaSaMember" xlink:title="csan_SinlogTecnologiaEmLogsticaSaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="csan_SinlogTecnologiaEmLogsticaSaMember" xlink:title="Definition : dei_EntityDomain to csan_SinlogTecnologiaEmLogsticaSaMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain_1" xlink:title="dei_EntityDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain_1" xlink:title="Definition : dei_LegalEntityAxis to dei_EntityDomain" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SignificantInvestmentsInAssociatesAxis" xlink:label="ifrs-full_SignificantInvestmentsInAssociatesAxis" xlink:title="ifrs-full_SignificantInvestmentsInAssociatesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable" xlink:to="ifrs-full_SignificantInvestmentsInAssociatesAxis" xlink:title="Definition : ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable to ifrs-full_SignificantInvestmentsInAssociatesAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForAssociatesMember" xlink:label="ifrs-full_EntitysTotalForAssociatesMember" xlink:title="ifrs-full_EntitysTotalForAssociatesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SignificantInvestmentsInAssociatesAxis" xlink:to="ifrs-full_EntitysTotalForAssociatesMember" xlink:title="Definition : ifrs-full_SignificantInvestmentsInAssociatesAxis to ifrs-full_EntitysTotalForAssociatesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_JanusBrasilParticipacoesSAMember" xlink:label="csan_JanusBrasilParticipacoesSAMember" xlink:title="csan_JanusBrasilParticipacoesSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForAssociatesMember" xlink:to="csan_JanusBrasilParticipacoesSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForAssociatesMember to csan_JanusBrasilParticipacoesSAMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_NovviLimitedLiabilityCompanyMember" xlink:label="csan_NovviLimitedLiabilityCompanyMember" xlink:title="csan_NovviLimitedLiabilityCompanyMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForAssociatesMember" xlink:to="csan_NovviLimitedLiabilityCompanyMember" xlink:title="Definition : ifrs-full_EntitysTotalForAssociatesMember to csan_NovviLimitedLiabilityCompanyMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OtherInvestmentsMember" xlink:label="csan_OtherInvestmentsMember" xlink:title="csan_OtherInvestmentsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForAssociatesMember" xlink:to="csan_OtherInvestmentsMember" xlink:title="Definition : ifrs-full_EntitysTotalForAssociatesMember to csan_OtherInvestmentsMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RadarIIPropriedadesAgricolasSAMember" xlink:label="csan_RadarIIPropriedadesAgricolasSAMember" xlink:title="csan_RadarIIPropriedadesAgricolasSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForAssociatesMember" xlink:to="csan_RadarIIPropriedadesAgricolasSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForAssociatesMember to csan_RadarIIPropriedadesAgricolasSAMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RadarPropriedadesAgricolasSAMember" xlink:label="csan_RadarPropriedadesAgricolasSAMember" xlink:title="csan_RadarPropriedadesAgricolasSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForAssociatesMember" xlink:to="csan_RadarPropriedadesAgricolasSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForAssociatesMember to csan_RadarPropriedadesAgricolasSAMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_TellusBrasilParticipacoesSAMember" xlink:label="csan_TellusBrasilParticipacoesSAMember" xlink:title="csan_TellusBrasilParticipacoesSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForAssociatesMember" xlink:to="csan_TellusBrasilParticipacoesSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForAssociatesMember to csan_TellusBrasilParticipacoesSAMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_UsinaSantaLuizaSAMember" xlink:label="csan_UsinaSantaLuizaSAMember" xlink:title="csan_UsinaSantaLuizaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForAssociatesMember" xlink:to="csan_UsinaSantaLuizaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForAssociatesMember to csan_UsinaSantaLuizaSAMember" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_InterestOfCosanLogisticaSaMember" xlink:label="csan_InterestOfCosanLogisticaSaMember" xlink:title="csan_InterestOfCosanLogisticaSaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForAssociatesMember" xlink:to="csan_InterestOfCosanLogisticaSaMember" xlink:title="Definition : ifrs-full_EntitysTotalForAssociatesMember to csan_InterestOfCosanLogisticaSaMember" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForAssociatesMember" xlink:label="ifrs-full_EntitysTotalForAssociatesMember_1" xlink:title="ifrs-full_EntitysTotalForAssociatesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SignificantInvestmentsInAssociatesAxis" xlink:to="ifrs-full_EntitysTotalForAssociatesMember_1" xlink:title="Definition : ifrs-full_SignificantInvestmentsInAssociatesAxis to ifrs-full_EntitysTotalForAssociatesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:label="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="ifrs-full_SignificantInvestmentsInSubsidiariesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable" xlink:to="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="Definition : ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable to ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AirportEnergyLimitedMember" xlink:label="csan_AirportEnergyLimitedMember" xlink:title="csan_AirportEnergyLimitedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_AirportEnergyLimitedMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_AirportEnergyLimitedMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AirportEnergyServicesLimitedMember" xlink:label="csan_AirportEnergyServicesLimitedMember" xlink:title="csan_AirportEnergyServicesLimitedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_AirportEnergyServicesLimitedMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_AirportEnergyServicesLimitedMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ALLArgentinaSAMember" xlink:label="csan_ALLArgentinaSAMember" xlink:title="csan_ALLArgentinaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ALLArgentinaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ALLArgentinaSAMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ALLArmazensGeraisLtdaMember" xlink:label="csan_ALLArmazensGeraisLtdaMember" xlink:title="csan_ALLArmazensGeraisLtdaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ALLArmazensGeraisLtdaMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ALLArmazensGeraisLtdaMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ALLCentralSAMember" xlink:label="csan_ALLCentralSAMember" xlink:title="csan_ALLCentralSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ALLCentralSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ALLCentralSAMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ALLMesopotamicaSAMember" xlink:label="csan_ALLMesopotamicaSAMember" xlink:title="csan_ALLMesopotamicaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ALLMesopotamicaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ALLMesopotamicaSAMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BoswellsSAMember" xlink:label="csan_BoswellsSAMember" xlink:title="csan_BoswellsSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_BoswellsSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_BoswellsSAMember" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BradoLogisticaeParticipacoesSAMember" xlink:label="csan_BradoLogisticaeParticipacoesSAMember" xlink:title="csan_BradoLogisticaeParticipacoesSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_BradoLogisticaeParticipacoesSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_BradoLogisticaeParticipacoesSAMember" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BradoLogisticaSAMember" xlink:label="csan_BradoLogisticaSAMember" xlink:title="csan_BradoLogisticaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_BradoLogisticaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_BradoLogisticaSAMember" xlink:type="arc" use="optional" order="8" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanBiomassaSAMember" xlink:label="csan_CosanBiomassaSAMember" xlink:title="csan_CosanBiomassaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanBiomassaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanBiomassaSAMember" xlink:type="arc" use="optional" order="9" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanCaymanIILimitedMember" xlink:label="csan_CosanCaymanIILimitedMember" xlink:title="csan_CosanCaymanIILimitedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanCaymanIILimitedMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanCaymanIILimitedMember" xlink:type="arc" use="optional" order="10" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanGlobalLimitedMember" xlink:label="csan_CosanGlobalLimitedMember" xlink:title="csan_CosanGlobalLimitedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanGlobalLimitedMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanGlobalLimitedMember" xlink:type="arc" use="optional" order="11" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanInvestimentoseParticipacoesSAMember" xlink:label="csan_CosanInvestimentoseParticipacoesSAMember" xlink:title="csan_CosanInvestimentoseParticipacoesSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanInvestimentoseParticipacoesSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanInvestimentoseParticipacoesSAMember" xlink:type="arc" use="optional" order="12" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLubesInvestmentsLimitedMember" xlink:label="csan_CosanLubesInvestmentsLimitedMember" xlink:title="csan_CosanLubesInvestmentsLimitedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanLubesInvestmentsLimitedMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanLubesInvestmentsLimitedMember" xlink:type="arc" use="optional" order="13" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLubrificanteseEspecialidadesSAMember" xlink:label="csan_CosanLubrificanteseEspecialidadesSAMember" xlink:title="csan_CosanLubrificanteseEspecialidadesSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanLubrificanteseEspecialidadesSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanLubrificanteseEspecialidadesSAMember" xlink:type="arc" use="optional" order="14" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLubrificantesSRLMember" xlink:label="csan_CosanLubrificantesSRLMember" xlink:title="csan_CosanLubrificantesSRLMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanLubrificantesSRLMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanLubrificantesSRLMember" xlink:type="arc" use="optional" order="15" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLuxembourgSAMember" xlink:label="csan_CosanLuxembourgSAMember" xlink:title="csan_CosanLuxembourgSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanLuxembourgSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanLuxembourgSAMember" xlink:type="arc" use="optional" order="16" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanOverseasLimitedMember" xlink:label="csan_CosanOverseasLimitedMember" xlink:title="csan_CosanOverseasLimitedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanOverseasLimitedMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanOverseasLimitedMember" xlink:type="arc" use="optional" order="17" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanParaguaySAMember" xlink:label="csan_CosanParaguaySAMember" xlink:title="csan_CosanParaguaySAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanParaguaySAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanParaguaySAMember" xlink:type="arc" use="optional" order="18" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanUSIncMember" xlink:label="csan_CosanUSIncMember" xlink:title="csan_CosanUSIncMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanUSIncMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanUSIncMember" xlink:type="arc" use="optional" order="19" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ElevacoesPortuariasSAMember" xlink:label="csan_ElevacoesPortuariasSAMember" xlink:title="csan_ElevacoesPortuariasSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ElevacoesPortuariasSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ElevacoesPortuariasSAMember" xlink:type="arc" use="optional" order="20" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IlhaTerminalDistribuicaoDeProdutosQuimicosMember" xlink:label="csan_IlhaTerminalDistribuicaoDeProdutosQuimicosMember" xlink:title="csan_IlhaTerminalDistribuicaoDeProdutosQuimicosMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_IlhaTerminalDistribuicaoDeProdutosQuimicosMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_IlhaTerminalDistribuicaoDeProdutosQuimicosMember" xlink:type="arc" use="optional" order="21" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LogispotArmazensGeraisSAMember" xlink:label="csan_LogispotArmazensGeraisSAMember" xlink:title="csan_LogispotArmazensGeraisSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_LogispotArmazensGeraisSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_LogispotArmazensGeraisSAMember" xlink:type="arc" use="optional" order="22" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LubrigrupoiiMember" xlink:label="csan_LubrigrupoiiMember" xlink:title="csan_LubrigrupoiiMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_LubrigrupoiiMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_LubrigrupoiiMember" xlink:type="arc" use="optional" order="23" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_MooveLubricantsLimitedMember" xlink:label="csan_MooveLubricantsLimitedMember" xlink:title="csan_MooveLubricantsLimitedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_MooveLubricantsLimitedMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_MooveLubricantsLimitedMember" xlink:type="arc" use="optional" order="24" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ParanaguaSAMember" xlink:label="csan_ParanaguaSAMember" xlink:title="csan_ParanaguaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ParanaguaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ParanaguaSAMember" xlink:type="arc" use="optional" order="25" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PasadenaEmpreendimentoseParticipacoesSAMember" xlink:label="csan_PasadenaEmpreendimentoseParticipacoesSAMember" xlink:title="csan_PasadenaEmpreendimentoseParticipacoesSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_PasadenaEmpreendimentoseParticipacoesSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_PasadenaEmpreendimentoseParticipacoesSAMember" xlink:type="arc" use="optional" order="26" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PaylySolucoesDePagamentosSAMember" xlink:label="csan_PaylySolucoesDePagamentosSAMember" xlink:title="csan_PaylySolucoesDePagamentosSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_PaylySolucoesDePagamentosSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_PaylySolucoesDePagamentosSAMember" xlink:type="arc" use="optional" order="27" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PortoferLtdaMember" xlink:label="csan_PortoferLtdaMember" xlink:title="csan_PortoferLtdaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_PortoferLtdaMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_PortoferLtdaMember" xlink:type="arc" use="optional" order="28" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoIntermodalSAMember" xlink:label="csan_RumoIntermodalSAMember" xlink:title="csan_RumoIntermodalSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoIntermodalSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoIntermodalSAMember" xlink:type="arc" use="optional" order="29" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoLuxembourgSarlMember" xlink:label="csan_RumoLuxembourgSarlMember" xlink:title="csan_RumoLuxembourgSarlMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoLuxembourgSarlMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoLuxembourgSarlMember" xlink:type="arc" use="optional" order="30" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoMalhaNorteSAMember" xlink:label="csan_RumoMalhaNorteSAMember" xlink:title="csan_RumoMalhaNorteSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoMalhaNorteSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoMalhaNorteSAMember" xlink:type="arc" use="optional" order="31" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoMalhaOesteSAMember" xlink:label="csan_RumoMalhaOesteSAMember" xlink:title="csan_RumoMalhaOesteSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoMalhaOesteSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoMalhaOesteSAMember" xlink:type="arc" use="optional" order="32" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoMalhaPaulistaSAMember" xlink:label="csan_RumoMalhaPaulistaSAMember" xlink:title="csan_RumoMalhaPaulistaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoMalhaPaulistaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoMalhaPaulistaSAMember" xlink:type="arc" use="optional" order="33" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoMalhaSulSAMember" xlink:label="csan_RumoMalhaSulSAMember" xlink:title="csan_RumoMalhaSulSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoMalhaSulSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoMalhaSulSAMember" xlink:type="arc" use="optional" order="34" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoSAMember" xlink:label="csan_RumoSAMember" xlink:title="csan_RumoSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoSAMember" xlink:type="arc" use="optional" order="35" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ServiciosDeInversionLogisticaIntegralesSAMember" xlink:label="csan_ServiciosDeInversionLogisticaIntegralesSAMember" xlink:title="csan_ServiciosDeInversionLogisticaIntegralesSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ServiciosDeInversionLogisticaIntegralesSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ServiciosDeInversionLogisticaIntegralesSAMember" xlink:type="arc" use="optional" order="36" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_StanbridgeGroupLimitedMember" xlink:label="csan_StanbridgeGroupLimitedMember" xlink:title="csan_StanbridgeGroupLimitedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_StanbridgeGroupLimitedMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_StanbridgeGroupLimitedMember" xlink:type="arc" use="optional" order="37" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_TTAMember" xlink:label="csan_TTAMember" xlink:title="csan_TTAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_TTAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_TTAMember" xlink:type="arc" use="optional" order="38" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_WessesxPetroleumLimitedMember" xlink:label="csan_WessesxPetroleumLimitedMember" xlink:title="csan_WessesxPetroleumLimitedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_WessesxPetroleumLimitedMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_WessesxPetroleumLimitedMember" xlink:type="arc" use="optional" order="39" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ZipLubeSAMember" xlink:label="csan_ZipLubeSAMember" xlink:title="csan_ZipLubeSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ZipLubeSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ZipLubeSAMember" xlink:type="arc" use="optional" order="40" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DistribuidoraDeGasParticipacoesSAMember" xlink:label="csan_DistribuidoraDeGasParticipacoesSAMember" xlink:title="csan_DistribuidoraDeGasParticipacoesSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_DistribuidoraDeGasParticipacoesSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_DistribuidoraDeGasParticipacoesSAMember" xlink:type="arc" use="optional" order="41" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CompanhiaDeGasDeSaoPauloComgasMember" xlink:label="csan_CompanhiaDeGasDeSaoPauloComgasMember" xlink:title="csan_CompanhiaDeGasDeSaoPauloComgasMember"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanSAMember" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLogisticaSAMember" xlink:label="csan_CosanLogisticaSAMember" xlink:title="csan_CosanLogisticaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanLogisticaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanLogisticaSAMember" xlink:type="arc" use="optional" order="8" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PaylyMember" xlink:label="csan_PaylyMember" xlink:title="csan_PaylyMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_PaylyMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_PaylyMember" xlink:type="arc" use="optional" order="9" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SinlogTecnologiaEmLogisticaSaMember" xlink:label="csan_SinlogTecnologiaEmLogisticaSaMember" xlink:title="csan_SinlogTecnologiaEmLogisticaSaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_SinlogTecnologiaEmLogisticaSaMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_SinlogTecnologiaEmLogisticaSaMember" xlink:type="arc" use="optional" order="10" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_TtaMember" xlink:label="csan_TtaMember" xlink:title="csan_TtaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_TtaMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_TtaMember" xlink:type="arc" use="optional" order="11" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLimitedPartnersBrasilConsultoriaLtdaMember" xlink:label="csan_CosanLimitedPartnersBrasilConsultoriaLtdaMember" xlink:title="csan_CosanLimitedPartnersBrasilConsultoriaLtdaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanLimitedPartnersBrasilConsultoriaLtdaMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanLimitedPartnersBrasilConsultoriaLtdaMember" xlink:type="arc" use="optional" order="12" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoSAMember" xlink:label="csan_RumoSAMember" xlink:title="csan_RumoSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoSAMember" xlink:type="arc" use="optional" order="13" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LogispotArmazensAgricolasSAMember" xlink:label="csan_LogispotArmazensAgricolasSAMember" xlink:title="csan_LogispotArmazensAgricolasSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_LogispotArmazensAgricolasSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_LogispotArmazensAgricolasSAMember" xlink:type="arc" use="optional" order="14" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OtherInvestmentsMember" xlink:label="csan_OtherInvestmentsMember" xlink:title="csan_OtherInvestmentsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_OtherInvestmentsMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_OtherInvestmentsMember" xlink:type="arc" use="optional" order="15" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLogisticaMember" xlink:label="csan_CosanLogisticaMember" xlink:title="csan_CosanLogisticaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanLogisticaMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanLogisticaMember" xlink:type="arc" use="optional" order="16" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:label="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:title="ifrs-full_CategoriesOfRelatedPartiesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_StatementOfFinancialStatementsTable" xlink:to="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:title="Definition : csan_StatementOfFinancialStatementsTable to ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:label="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:title="ifrs-full_EntitysTotalForRelatedPartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:to="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:title="Definition : ifrs-full_CategoriesOfRelatedPartiesAxis to ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SubsidiariesMember" xlink:label="ifrs-full_SubsidiariesMember" xlink:title="ifrs-full_SubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="ifrs-full_SubsidiariesMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to ifrs-full_SubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:label="ifrs-full_EntitysTotalForRelatedPartiesMember_1" xlink:title="ifrs-full_EntitysTotalForRelatedPartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:to="ifrs-full_EntitysTotalForRelatedPartiesMember_1" xlink:title="Definition : ifrs-full_CategoriesOfRelatedPartiesAxis to ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/FinancialAssetsAndLiabilitiesSummaryOfTradeReceivablesDetail">
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfTradeReceivablesLineItems" xlink:label="csan_DisclosureOfTradeReceivablesLineItems" xlink:title="csan_DisclosureOfTradeReceivablesLineItems"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CurrentTradeReceivables" xlink:label="ifrs-full_CurrentTradeReceivables" xlink:title="ifrs-full_CurrentTradeReceivables"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfTradeReceivablesLineItems" xlink:to="ifrs-full_CurrentTradeReceivables" xlink:title="Definition : csan_DisclosureOfTradeReceivablesLineItems to ifrs-full_CurrentTradeReceivables" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfTradeReceivablesTable" xlink:label="csan_DisclosureOfTradeReceivablesTable" xlink:title="csan_DisclosureOfTradeReceivablesTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="csan_DisclosureOfTradeReceivablesLineItems" xlink:to="csan_DisclosureOfTradeReceivablesTable" xlink:title="Definition : csan_DisclosureOfTradeReceivablesLineItems to csan_DisclosureOfTradeReceivablesTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:label="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:title="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfTradeReceivablesTable" xlink:to="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:title="Definition : csan_DisclosureOfTradeReceivablesTable to ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CarryingAmountMember" xlink:label="ifrs-full_CarryingAmountMember" xlink:title="ifrs-full_CarryingAmountMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:to="ifrs-full_CarryingAmountMember" xlink:title="Definition : ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis to ifrs-full_CarryingAmountMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GrossCarryingAmountMember" xlink:label="ifrs-full_GrossCarryingAmountMember" xlink:title="ifrs-full_GrossCarryingAmountMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_CarryingAmountMember" xlink:to="ifrs-full_GrossCarryingAmountMember" xlink:title="Definition : ifrs-full_CarryingAmountMember to ifrs-full_GrossCarryingAmountMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_AccumulatedImpairmentMember" xlink:label="ifrs-full_AccumulatedImpairmentMember" xlink:title="ifrs-full_AccumulatedImpairmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_CarryingAmountMember" xlink:to="ifrs-full_AccumulatedImpairmentMember" xlink:title="Definition : ifrs-full_CarryingAmountMember to ifrs-full_AccumulatedImpairmentMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CarryingAmountMember" xlink:label="ifrs-full_CarryingAmountMember_1" xlink:title="ifrs-full_CarryingAmountMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:to="ifrs-full_CarryingAmountMember_1" xlink:title="Definition : ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis to ifrs-full_CarryingAmountMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ReceivablesByBillingStatusTypeAxis" xlink:label="csan_ReceivablesByBillingStatusTypeAxis" xlink:title="csan_ReceivablesByBillingStatusTypeAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfTradeReceivablesTable" xlink:to="csan_ReceivablesByBillingStatusTypeAxis" xlink:title="Definition : csan_DisclosureOfTradeReceivablesTable to csan_ReceivablesByBillingStatusTypeAxis" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ReceivablesBillingStatus1Domain" xlink:label="csan_ReceivablesBillingStatus1Domain" xlink:title="csan_ReceivablesBillingStatus1Domain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="csan_ReceivablesByBillingStatusTypeAxis" xlink:to="csan_ReceivablesBillingStatus1Domain" xlink:title="Definition : csan_ReceivablesByBillingStatusTypeAxis to csan_ReceivablesBillingStatus1Domain" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_UnbilledReceivablesMember" xlink:label="csan_UnbilledReceivablesMember" xlink:title="csan_UnbilledReceivablesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_ReceivablesBillingStatus1Domain" xlink:to="csan_UnbilledReceivablesMember" xlink:title="Definition : csan_ReceivablesBillingStatus1Domain to csan_UnbilledReceivablesMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ReceivablesBillingStatus1Domain" xlink:label="csan_ReceivablesBillingStatus1Domain_1" xlink:title="csan_ReceivablesBillingStatus1Domain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="csan_ReceivablesByBillingStatusTypeAxis" xlink:to="csan_ReceivablesBillingStatus1Domain_1" xlink:title="Definition : csan_ReceivablesByBillingStatusTypeAxis to csan_ReceivablesBillingStatus1Domain" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GeographicalAreasAxis" xlink:label="ifrs-full_GeographicalAreasAxis" xlink:title="ifrs-full_GeographicalAreasAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfTradeReceivablesTable" xlink:to="ifrs-full_GeographicalAreasAxis" xlink:title="Definition : csan_DisclosureOfTradeReceivablesTable to ifrs-full_GeographicalAreasAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GeographicalAreasMember" xlink:label="ifrs-full_GeographicalAreasMember" xlink:title="ifrs-full_GeographicalAreasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_GeographicalAreasAxis" xlink:to="ifrs-full_GeographicalAreasMember" xlink:title="Definition : ifrs-full_GeographicalAreasAxis to ifrs-full_GeographicalAreasMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DomesticBrazilianReaisMember" xlink:label="csan_DomesticBrazilianReaisMember" xlink:title="csan_DomesticBrazilianReaisMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_GeographicalAreasMember" xlink:to="csan_DomesticBrazilianReaisMember" xlink:title="Definition : ifrs-full_GeographicalAreasMember to csan_DomesticBrazilianReaisMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ExportForeignCurrencyMember" xlink:label="csan_ExportForeignCurrencyMember" xlink:title="csan_ExportForeignCurrencyMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_GeographicalAreasMember" xlink:to="csan_ExportForeignCurrencyMember" xlink:title="Definition : ifrs-full_GeographicalAreasMember to csan_ExportForeignCurrencyMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GeographicalAreasMember" xlink:label="ifrs-full_GeographicalAreasMember_1" xlink:title="ifrs-full_GeographicalAreasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_GeographicalAreasAxis" xlink:to="ifrs-full_GeographicalAreasMember_1" xlink:title="Definition : ifrs-full_GeographicalAreasAxis to ifrs-full_GeographicalAreasMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NoncurrentTradeReceivables" xlink:label="ifrs-full_NoncurrentTradeReceivables" xlink:title="ifrs-full_NoncurrentTradeReceivables"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfTradeReceivablesLineItems" xlink:to="ifrs-full_NoncurrentTradeReceivables" xlink:title="Definition : csan_DisclosureOfTradeReceivablesLineItems to ifrs-full_NoncurrentTradeReceivables" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TradeReceivables" xlink:label="ifrs-full_TradeReceivables" xlink:title="ifrs-full_TradeReceivables"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfTradeReceivablesLineItems" xlink:to="ifrs-full_TradeReceivables" xlink:title="Definition : csan_DisclosureOfTradeReceivablesLineItems to ifrs-full_TradeReceivables" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
</link:definitionLink>
<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/CorporatereorganizationAdditionalInformationDetail">
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfBusinessCombinationsLineItems" xlink:label="ifrs-full_DisclosureOfBusinessCombinationsLineItems" xlink:title="ifrs-full_DisclosureOfBusinessCombinationsLineItems"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ConversionRatioPerShareOfAcquireeUponMerger" xlink:label="csan_ConversionRatioPerShareOfAcquireeUponMerger" xlink:title="csan_ConversionRatioPerShareOfAcquireeUponMerger"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfBusinessCombinationsLineItems" xlink:to="csan_ConversionRatioPerShareOfAcquireeUponMerger" xlink:title="Definition : ifrs-full_DisclosureOfBusinessCombinationsLineItems to csan_ConversionRatioPerShareOfAcquireeUponMerger" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ConversionRatioPerShareOfAcquirerUponMerger" xlink:label="csan_ConversionRatioPerShareOfAcquirerUponMerger" xlink:title="csan_ConversionRatioPerShareOfAcquirerUponMerger"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfBusinessCombinationsLineItems" xlink:to="csan_ConversionRatioPerShareOfAcquirerUponMerger" xlink:title="Definition : ifrs-full_DisclosureOfBusinessCombinationsLineItems to csan_ConversionRatioPerShareOfAcquirerUponMerger" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfBusinessCombinationsTable" xlink:label="ifrs-full_DisclosureOfBusinessCombinationsTable" xlink:title="ifrs-full_DisclosureOfBusinessCombinationsTable"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ComgasMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ComgasMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable" xlink:to="ifrs-full_RangeAxis" xlink:title="Definition : ifrs-full_DisclosureOfTransactionsBetweenRelatedPartiesTable to ifrs-full_RangeAxis" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember" xlink:title="ifrs-full_RangesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_RangeAxis" xlink:to="ifrs-full_RangesMember" xlink:title="Definition : ifrs-full_RangeAxis to ifrs-full_RangesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RangesMember" xlink:to="ifrs-full_BottomOfRangeMember" xlink:title="Definition : ifrs-full_RangesMember to ifrs-full_BottomOfRangeMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RangesMember" xlink:to="ifrs-full_TopOfRangeMember" xlink:title="Definition : ifrs-full_RangesMember to ifrs-full_TopOfRangeMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember_1" xlink:title="ifrs-full_RangesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_RangeAxis" xlink:to="ifrs-full_RangesMember_1" xlink:title="Definition : ifrs-full_RangeAxis to ifrs-full_RangesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfBusinessCombinationsLineItems" xlink:to="ifrs-full_CashTransferred" xlink:title="Definition : ifrs-full_DisclosureOfBusinessCombinationsLineItems to ifrs-full_CashTransferred" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfBusinessCombinationsLineItems" xlink:to="ifrs-full_GoodwillRecognisedAsOfAcquisitionDate" xlink:title="Definition : ifrs-full_DisclosureOfBusinessCombinationsLineItems to ifrs-full_GoodwillRecognisedAsOfAcquisitionDate" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfBusinessCombinationsLineItems" xlink:to="ifrs-full_ParValuePerShare" xlink:title="Definition : ifrs-full_DisclosureOfBusinessCombinationsLineItems to ifrs-full_ParValuePerShare" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfJointVenturesTable" xlink:label="ifrs-full_DisclosureOfJointVenturesTable" xlink:title="ifrs-full_DisclosureOfJointVenturesTable"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfJointVenturesTable" xlink:to="ifrs-full_JointVenturesAxis" xlink:title="Definition : ifrs-full_DisclosureOfJointVenturesTable to ifrs-full_JointVenturesAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForJointVenturesMember" xlink:label="ifrs-full_EntitysTotalForJointVenturesMember" xlink:title="ifrs-full_EntitysTotalForJointVenturesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_JointVenturesAxis" xlink:to="ifrs-full_EntitysTotalForJointVenturesMember" xlink:title="Definition : ifrs-full_JointVenturesAxis to ifrs-full_EntitysTotalForJointVenturesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForJointVenturesMember" xlink:to="csan_RaizenCombustiveisSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForJointVenturesMember to csan_RaizenCombustiveisSAMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RaizenEnergiaSAMember" xlink:label="csan_RaizenEnergiaSAMember" xlink:title="csan_RaizenEnergiaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForJointVenturesMember" xlink:to="csan_RaizenEnergiaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForJointVenturesMember to csan_RaizenEnergiaSAMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForJointVenturesMember" xlink:label="ifrs-full_EntitysTotalForJointVenturesMember_1" xlink:title="ifrs-full_EntitysTotalForJointVenturesMember"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfJointVenturesTable" xlink:to="ifrs-full_NewIFRSsAxis" xlink:title="Definition : ifrs-full_DisclosureOfJointVenturesTable to ifrs-full_NewIFRSsAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NewIFRSsMember" xlink:label="ifrs-full_NewIFRSsMember" xlink:title="ifrs-full_NewIFRSsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_NewIFRSsAxis" xlink:to="ifrs-full_NewIFRSsMember" xlink:title="Definition : ifrs-full_NewIFRSsAxis to ifrs-full_NewIFRSsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_NewIFRSsMember" xlink:to="csan_IfrsSixteenMember" xlink:title="Definition : ifrs-full_NewIFRSsMember to csan_IfrsSixteenMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NewIFRSsMember" xlink:label="ifrs-full_NewIFRSsMember_1" xlink:title="ifrs-full_NewIFRSsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_NewIFRSsAxis" xlink:to="ifrs-full_NewIFRSsMember_1" xlink:title="Definition : ifrs-full_NewIFRSsAxis to ifrs-full_NewIFRSsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfJointVenturesTable" xlink:to="csan_IncomeStatementAxis" xlink:title="Definition : ifrs-full_DisclosureOfJointVenturesTable to csan_IncomeStatementAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IncomeStatementDomain" xlink:label="csan_IncomeStatementDomain" xlink:title="csan_IncomeStatementDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="csan_IncomeStatementAxis" xlink:to="csan_IncomeStatementDomain" xlink:title="Definition : csan_IncomeStatementAxis to csan_IncomeStatementDomain" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IcmsExclusionMember" xlink:label="csan_IcmsExclusionMember" xlink:title="csan_IcmsExclusionMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_IncomeStatementDomain" xlink:to="csan_IcmsExclusionMember" xlink:title="Definition : csan_IncomeStatementDomain to csan_IcmsExclusionMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SaleToFemsaComercioMember" xlink:label="csan_SaleToFemsaComercioMember" xlink:title="csan_SaleToFemsaComercioMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_IncomeStatementDomain" xlink:to="csan_SaleToFemsaComercioMember" xlink:title="Definition : csan_IncomeStatementDomain to csan_SaleToFemsaComercioMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IncomeStatementDomain" xlink:label="csan_IncomeStatementDomain_1" xlink:title="csan_IncomeStatementDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="csan_IncomeStatementAxis" xlink:to="csan_IncomeStatementDomain_1" xlink:title="Definition : csan_IncomeStatementAxis to csan_IncomeStatementDomain" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfJointVenturesTable" xlink:to="ifrs-full_JointVenturesAxis" xlink:title="Definition : ifrs-full_DisclosureOfJointVenturesTable to ifrs-full_JointVenturesAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForJointVenturesMember" xlink:label="ifrs-full_EntitysTotalForJointVenturesMember" xlink:title="ifrs-full_EntitysTotalForJointVenturesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_JointVenturesAxis" xlink:to="ifrs-full_EntitysTotalForJointVenturesMember" xlink:title="Definition : ifrs-full_JointVenturesAxis to ifrs-full_EntitysTotalForJointVenturesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RaizenCombustiveisSAMember" xlink:label="csan_RaizenCombustiveisSAMember" xlink:title="csan_RaizenCombustiveisSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForJointVenturesMember" xlink:to="csan_RaizenCombustiveisSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForJointVenturesMember to csan_RaizenCombustiveisSAMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForJointVenturesMember" xlink:to="csan_RaizenEnergiaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForJointVenturesMember to csan_RaizenEnergiaSAMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForJointVenturesMember" xlink:label="ifrs-full_EntitysTotalForJointVenturesMember_1" xlink:title="ifrs-full_EntitysTotalForJointVenturesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_JointVenturesAxis" xlink:to="ifrs-full_EntitysTotalForJointVenturesMember_1" xlink:title="Definition : ifrs-full_JointVenturesAxis to ifrs-full_EntitysTotalForJointVenturesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DividendsReceivedFromJointVentures" xlink:label="csan_DividendsReceivedFromJointVentures" xlink:title="csan_DividendsReceivedFromJointVentures"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_IncreaseDecreaseInAccountingEstimate" xlink:label="ifrs-full_IncreaseDecreaseInAccountingEstimate" xlink:title="ifrs-full_IncreaseDecreaseInAccountingEstimate"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfJointVenturesLineItems" xlink:to="ifrs-full_IncreaseDecreaseInAccountingEstimate" xlink:title="Definition : ifrs-full_DisclosureOfJointVenturesLineItems to ifrs-full_IncreaseDecreaseInAccountingEstimate" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_InterestOnCapital" xlink:label="csan_InterestOnCapital" xlink:title="csan_InterestOnCapital"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfJointVenturesLineItems" xlink:to="csan_InterestOnCapital" xlink:title="Definition : ifrs-full_DisclosureOfJointVenturesLineItems to csan_InterestOnCapital" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_InvestmentsInJointVenturesAccountedForUsingEquityMethod" xlink:label="ifrs-full_InvestmentsInJointVenturesAccountedForUsingEquityMethod" xlink:title="ifrs-full_InvestmentsInJointVenturesAccountedForUsingEquityMethod"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfJointVenturesLineItems" xlink:to="ifrs-full_InvestmentsInJointVenturesAccountedForUsingEquityMethod" xlink:title="Definition : ifrs-full_DisclosureOfJointVenturesLineItems to ifrs-full_InvestmentsInJointVenturesAccountedForUsingEquityMethod" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfJointVenturesLineItems" xlink:to="csan_NumberOfSharesHeldByParent" xlink:title="Definition : ifrs-full_DisclosureOfJointVenturesLineItems to csan_NumberOfSharesHeldByParent" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfJointVenturesLineItems" xlink:to="ifrs-full_NumberOfSharesIssued" xlink:title="Definition : ifrs-full_DisclosureOfJointVenturesLineItems to ifrs-full_NumberOfSharesIssued" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfJointVenturesLineItems" xlink:to="ifrs-full_ProportionOfOwnershipInterestInJointVenture" xlink:title="Definition : ifrs-full_DisclosureOfJointVenturesLineItems to ifrs-full_ProportionOfOwnershipInterestInJointVenture" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfJointVenturesLineItems" xlink:to="ifrs-full_ShareOfProfitLossOfJointVenturesAccountedForUsingEquityMethod" xlink:title="Definition : ifrs-full_DisclosureOfJointVenturesLineItems to ifrs-full_ShareOfProfitLossOfJointVenturesAccountedForUsingEquityMethod" xlink:type="arc" use="optional" order="8" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfJointVenturesLineItems" xlink:to="csan_ShareOfTotalComprehensiveIncomeOfJointVenturesAccountedForUsingEquityMethod" xlink:title="Definition : ifrs-full_DisclosureOfJointVenturesLineItems to csan_ShareOfTotalComprehensiveIncomeOfJointVenturesAccountedForUsingEquityMethod" xlink:type="arc" use="optional" order="9" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="ifrs-full_ComprehensiveIncome" xlink:title="Definition : srt_CondensedFinancialStatementsCaptionsLineItems to ifrs-full_ComprehensiveIncome" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ComprehensiveIncomeAttributableToNoncontrollingInterests" xlink:label="ifrs-full_ComprehensiveIncomeAttributableToNoncontrollingInterests" xlink:title="ifrs-full_ComprehensiveIncomeAttributableToNoncontrollingInterests"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="ifrs-full_ComprehensiveIncomeAttributableToNoncontrollingInterests" xlink:title="Definition : srt_CondensedFinancialStatementsCaptionsLineItems to ifrs-full_ComprehensiveIncomeAttributableToNoncontrollingInterests" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DividendsPaid" xlink:label="ifrs-full_DividendsPaid" xlink:title="ifrs-full_DividendsPaid"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="ifrs-full_DividendsPaid" xlink:title="Definition : srt_CondensedFinancialStatementsCaptionsLineItems to ifrs-full_DividendsPaid" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_IncomeTaxExpenseContinuingOperations" xlink:label="ifrs-full_IncomeTaxExpenseContinuingOperations" xlink:title="ifrs-full_IncomeTaxExpenseContinuingOperations"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="ifrs-full_IncomeTaxExpenseContinuingOperations" xlink:title="Definition : srt_CondensedFinancialStatementsCaptionsLineItems to ifrs-full_IncomeTaxExpenseContinuingOperations" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="ifrs-full_OtherComprehensiveIncome" xlink:title="Definition : srt_CondensedFinancialStatementsCaptionsLineItems to ifrs-full_OtherComprehensiveIncome" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="ifrs-full_ProfitLoss" xlink:title="Definition : srt_CondensedFinancialStatementsCaptionsLineItems to ifrs-full_ProfitLoss" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProfitLossBeforeTax" xlink:label="ifrs-full_ProfitLossBeforeTax" xlink:title="ifrs-full_ProfitLossBeforeTax"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="ifrs-full_ProfitLossBeforeTax" xlink:title="Definition : srt_CondensedFinancialStatementsCaptionsLineItems to ifrs-full_ProfitLossBeforeTax" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_Revenue" xlink:label="ifrs-full_Revenue" xlink:title="ifrs-full_Revenue"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="ifrs-full_Revenue" xlink:title="Definition : srt_CondensedFinancialStatementsCaptionsLineItems to ifrs-full_Revenue" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_StatementOfFinancialStatementsTable" xlink:label="csan_StatementOfFinancialStatementsTable" xlink:title="csan_StatementOfFinancialStatementsTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="csan_StatementOfFinancialStatementsTable" xlink:title="Definition : srt_CondensedFinancialStatementsCaptionsLineItems to csan_StatementOfFinancialStatementsTable" xlink:type="arc" use="optional" order="8" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:label="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:title="ifrs-full_CategoriesOfRelatedPartiesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_StatementOfFinancialStatementsTable" xlink:to="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:title="Definition : csan_StatementOfFinancialStatementsTable to ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:label="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:title="ifrs-full_EntitysTotalForRelatedPartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:to="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:title="Definition : ifrs-full_CategoriesOfRelatedPartiesAxis to ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CompanhiaDeGasDeSaoPauloMember" xlink:label="csan_CompanhiaDeGasDeSaoPauloMember" xlink:title="csan_CompanhiaDeGasDeSaoPauloMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_CompanhiaDeGasDeSaoPauloMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_CompanhiaDeGasDeSaoPauloMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLogisticaSAMember" xlink:label="csan_CosanLogisticaSAMember" xlink:title="csan_CosanLogisticaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_CosanLogisticaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_CosanLogisticaSAMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanSAMember" xlink:label="csan_CosanSAMember" xlink:title="csan_CosanSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_CosanSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_CosanSAMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoSAMember" xlink:label="csan_RumoSAMember" xlink:title="csan_RumoSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_RumoSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_RumoSAMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CompassGasEEnergiaSAMember" xlink:label="csan_CompassGasEEnergiaSAMember" xlink:title="csan_CompassGasEEnergiaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_CompassGasEEnergiaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_CompassGasEEnergiaSAMember" xlink:type="arc" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ComgasMember" xlink:label="csan_ComgasMember" xlink:title="csan_ComgasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_ComgasMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_ComgasMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SinlogTecnologiaEmLogisticaSaMember" xlink:label="csan_SinlogTecnologiaEmLogisticaSaMember" xlink:title="csan_SinlogTecnologiaEmLogisticaSaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_SinlogTecnologiaEmLogisticaSaMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_SinlogTecnologiaEmLogisticaSaMember" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:label="ifrs-full_EntitysTotalForRelatedPartiesMember_1" xlink:title="ifrs-full_EntitysTotalForRelatedPartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:to="ifrs-full_EntitysTotalForRelatedPartiesMember_1" xlink:title="Definition : ifrs-full_CategoriesOfRelatedPartiesAxis to ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
</link:definitionLink>
<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/PropertyplantandequipmentintangibleassetsgoodwillrightofuseassetsandcontractassetsSummaryofDepreciationonStraightlineBasisOvertheEstimatedUsefullifeofAssetsDetail">
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:label="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:title="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:label="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:title="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:to="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems to ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:type="arc" use="optional" order="0" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:label="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:title="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:to="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable to ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PropertyPlantAndEquipmentMember" xlink:label="ifrs-full_PropertyPlantAndEquipmentMember" xlink:title="ifrs-full_PropertyPlantAndEquipmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:to="ifrs-full_PropertyPlantAndEquipmentMember" xlink:title="Definition : ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis to ifrs-full_PropertyPlantAndEquipmentMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BuildingsAndImprovementsMember" xlink:label="csan_BuildingsAndImprovementsMember" xlink:title="csan_BuildingsAndImprovementsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="csan_BuildingsAndImprovementsMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to csan_BuildingsAndImprovementsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ComputerEquipmentMember" xlink:label="ifrs-full_ComputerEquipmentMember" xlink:title="ifrs-full_ComputerEquipmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="ifrs-full_ComputerEquipmentMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to ifrs-full_ComputerEquipmentMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_FixturesAndFittingsMember" xlink:label="ifrs-full_FixturesAndFittingsMember" xlink:title="ifrs-full_FixturesAndFittingsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="ifrs-full_FixturesAndFittingsMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to ifrs-full_FixturesAndFittingsMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LocomotivesMember" xlink:label="csan_LocomotivesMember" xlink:title="csan_LocomotivesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="csan_LocomotivesMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to csan_LocomotivesMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_MachineryEquipmentAndFacilitiesMember" xlink:label="csan_MachineryEquipmentAndFacilitiesMember" xlink:title="csan_MachineryEquipmentAndFacilitiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="csan_MachineryEquipmentAndFacilitiesMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to csan_MachineryEquipmentAndFacilitiesMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PermanentRailwaysMember" xlink:label="csan_PermanentRailwaysMember" xlink:title="csan_PermanentRailwaysMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="csan_PermanentRailwaysMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to csan_PermanentRailwaysMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RailcarsMember" xlink:label="csan_RailcarsMember" xlink:title="csan_RailcarsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="csan_RailcarsMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to csan_RailcarsMember" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_VehiclesMember" xlink:label="ifrs-full_VehiclesMember" xlink:title="ifrs-full_VehiclesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="ifrs-full_VehiclesMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to ifrs-full_VehiclesMember" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PropertyPlantAndEquipmentMember" xlink:label="ifrs-full_PropertyPlantAndEquipmentMember_1" xlink:title="ifrs-full_PropertyPlantAndEquipmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:to="ifrs-full_PropertyPlantAndEquipmentMember_1" xlink:title="Definition : ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis to ifrs-full_PropertyPlantAndEquipmentMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangeAxis" xlink:label="ifrs-full_RangeAxis" xlink:title="ifrs-full_RangeAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:to="ifrs-full_RangeAxis" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable to ifrs-full_RangeAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember" xlink:title="ifrs-full_RangesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_RangeAxis" xlink:to="ifrs-full_RangesMember" xlink:title="Definition : ifrs-full_RangeAxis to ifrs-full_RangesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BottomOfRangeMember" xlink:label="ifrs-full_BottomOfRangeMember" xlink:title="ifrs-full_BottomOfRangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RangesMember" xlink:to="ifrs-full_BottomOfRangeMember" xlink:title="Definition : ifrs-full_RangesMember to ifrs-full_BottomOfRangeMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TopOfRangeMember" xlink:label="ifrs-full_TopOfRangeMember" xlink:title="ifrs-full_TopOfRangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RangesMember" xlink:to="ifrs-full_TopOfRangeMember" xlink:title="Definition : ifrs-full_RangesMember to ifrs-full_TopOfRangeMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember_1" xlink:title="ifrs-full_RangesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_RangeAxis" xlink:to="ifrs-full_RangesMember_1" xlink:title="Definition : ifrs-full_RangeAxis to ifrs-full_RangesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PercentageOfDepreciation" xlink:label="csan_PercentageOfDepreciation" xlink:title="csan_PercentageOfDepreciation"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:to="csan_PercentageOfDepreciation" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems to csan_PercentageOfDepreciation" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
</link:definitionLink>
<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/PropertyplantandequipmentintangibleassetsgoodwillrightofuseassetsandcontractassetsScheduleofPropertyPlantandEquipmentDetail">
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:label="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:title="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_AcquisitionsThroughBusinessCombinationsPropertyPlantAndEquipment" xlink:label="ifrs-full_AcquisitionsThroughBusinessCombinationsPropertyPlantAndEquipment" xlink:title="ifrs-full_AcquisitionsThroughBusinessCombinationsPropertyPlantAndEquipment"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:to="ifrs-full_AcquisitionsThroughBusinessCombinationsPropertyPlantAndEquipment" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems to ifrs-full_AcquisitionsThroughBusinessCombinationsPropertyPlantAndEquipment" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_AdditionsOtherThanThroughBusinessCombinationsPropertyPlantAndEquipment" xlink:label="ifrs-full_AdditionsOtherThanThroughBusinessCombinationsPropertyPlantAndEquipment" xlink:title="ifrs-full_AdditionsOtherThanThroughBusinessCombinationsPropertyPlantAndEquipment"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:to="ifrs-full_AdditionsOtherThanThroughBusinessCombinationsPropertyPlantAndEquipment" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems to ifrs-full_AdditionsOtherThanThroughBusinessCombinationsPropertyPlantAndEquipment" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:label="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:title="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:to="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems to ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:type="arc" use="optional" order="2" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:label="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:title="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:to="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable to ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CarryingAmountMember" xlink:label="ifrs-full_CarryingAmountMember" xlink:title="ifrs-full_CarryingAmountMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:to="ifrs-full_CarryingAmountMember" xlink:title="Definition : ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis to ifrs-full_CarryingAmountMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_AccumulatedDepreciationAndAmortisationMember" xlink:label="ifrs-full_AccumulatedDepreciationAndAmortisationMember" xlink:title="ifrs-full_AccumulatedDepreciationAndAmortisationMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_CarryingAmountMember" xlink:to="ifrs-full_AccumulatedDepreciationAndAmortisationMember" xlink:title="Definition : ifrs-full_CarryingAmountMember to ifrs-full_AccumulatedDepreciationAndAmortisationMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GrossCarryingAmountMember" xlink:label="ifrs-full_GrossCarryingAmountMember" xlink:title="ifrs-full_GrossCarryingAmountMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_CarryingAmountMember" xlink:to="ifrs-full_GrossCarryingAmountMember" xlink:title="Definition : ifrs-full_CarryingAmountMember to ifrs-full_GrossCarryingAmountMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CarryingAmountMember" xlink:label="ifrs-full_CarryingAmountMember_1" xlink:title="ifrs-full_CarryingAmountMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:to="ifrs-full_CarryingAmountMember_1" xlink:title="Definition : ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis to ifrs-full_CarryingAmountMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:label="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:title="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:to="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable to ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PropertyPlantAndEquipmentMember" xlink:label="ifrs-full_PropertyPlantAndEquipmentMember" xlink:title="ifrs-full_PropertyPlantAndEquipmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:to="ifrs-full_PropertyPlantAndEquipmentMember" xlink:title="Definition : ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis to ifrs-full_PropertyPlantAndEquipmentMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ConstructionInProgressMember" xlink:label="ifrs-full_ConstructionInProgressMember" xlink:title="ifrs-full_ConstructionInProgressMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="ifrs-full_ConstructionInProgressMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to ifrs-full_ConstructionInProgressMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_LandAndBuildingsMember" xlink:label="ifrs-full_LandAndBuildingsMember" xlink:title="ifrs-full_LandAndBuildingsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="ifrs-full_LandAndBuildingsMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to ifrs-full_LandAndBuildingsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_MachineryEquipmentAndFacilitiesMember" xlink:label="csan_MachineryEquipmentAndFacilitiesMember" xlink:title="csan_MachineryEquipmentAndFacilitiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="csan_MachineryEquipmentAndFacilitiesMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to csan_MachineryEquipmentAndFacilitiesMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_OtherPropertyPlantAndEquipmentMember" xlink:label="ifrs-full_OtherPropertyPlantAndEquipmentMember" xlink:title="ifrs-full_OtherPropertyPlantAndEquipmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="ifrs-full_OtherPropertyPlantAndEquipmentMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to ifrs-full_OtherPropertyPlantAndEquipmentMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PermanentEasementMember" xlink:label="csan_PermanentEasementMember" xlink:title="csan_PermanentEasementMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="csan_PermanentEasementMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to csan_PermanentEasementMember" xlink:type="arc" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PermanentRailwaysMember" xlink:label="csan_PermanentRailwaysMember" xlink:title="csan_PermanentRailwaysMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="csan_PermanentRailwaysMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to csan_PermanentRailwaysMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RailcarsAndLocomotivesMember" xlink:label="csan_RailcarsAndLocomotivesMember" xlink:title="csan_RailcarsAndLocomotivesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="csan_RailcarsAndLocomotivesMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to csan_RailcarsAndLocomotivesMember" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PropertyPlantAndEquipmentMember" xlink:label="ifrs-full_PropertyPlantAndEquipmentMember_1" xlink:title="ifrs-full_PropertyPlantAndEquipmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:to="ifrs-full_PropertyPlantAndEquipmentMember_1" xlink:title="Definition : ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis to ifrs-full_PropertyPlantAndEquipmentMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis" xlink:label="ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis" xlink:title="ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:to="ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable to ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RestatedMember" xlink:label="ifrs-full_RestatedMember" xlink:title="ifrs-full_RestatedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis" xlink:to="ifrs-full_RestatedMember" xlink:title="Definition : ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis to ifrs-full_RestatedMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PreviouslyStatedMember" xlink:label="ifrs-full_PreviouslyStatedMember" xlink:title="ifrs-full_PreviouslyStatedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RestatedMember" xlink:to="ifrs-full_PreviouslyStatedMember" xlink:title="Definition : ifrs-full_RestatedMember to ifrs-full_PreviouslyStatedMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_IncreaseDecreaseDueToChangesInAccountingPolicyAndCorrectionsOfPriorPeriodErrorsMember" xlink:label="ifrs-full_IncreaseDecreaseDueToChangesInAccountingPolicyAndCorrectionsOfPriorPeriodErrorsMember" xlink:title="ifrs-full_IncreaseDecreaseDueToChangesInAccountingPolicyAndCorrectionsOfPriorPeriodErrorsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RestatedMember" xlink:to="ifrs-full_IncreaseDecreaseDueToChangesInAccountingPolicyAndCorrectionsOfPriorPeriodErrorsMember" xlink:title="Definition : ifrs-full_RestatedMember to ifrs-full_IncreaseDecreaseDueToChangesInAccountingPolicyAndCorrectionsOfPriorPeriodErrorsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RestatedMember" xlink:label="ifrs-full_RestatedMember_1" xlink:title="ifrs-full_RestatedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis" xlink:to="ifrs-full_RestatedMember_1" xlink:title="Definition : ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis to ifrs-full_RestatedMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ImpairmentLossRecognisedInProfitOrLossPropertyPlantAndEquipment" xlink:label="ifrs-full_ImpairmentLossRecognisedInProfitOrLossPropertyPlantAndEquipment" xlink:title="ifrs-full_ImpairmentLossRecognisedInProfitOrLossPropertyPlantAndEquipment"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:to="ifrs-full_ImpairmentLossRecognisedInProfitOrLossPropertyPlantAndEquipment" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems to ifrs-full_ImpairmentLossRecognisedInProfitOrLossPropertyPlantAndEquipment" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IncreaseDecreaseThroughDisposalPropertyPlantAndEquipment" xlink:label="csan_IncreaseDecreaseThroughDisposalPropertyPlantAndEquipment" xlink:title="csan_IncreaseDecreaseThroughDisposalPropertyPlantAndEquipment"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:to="csan_IncreaseDecreaseThroughDisposalPropertyPlantAndEquipment" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems to csan_IncreaseDecreaseThroughDisposalPropertyPlantAndEquipment" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesPropertyPlantAndEquipment" xlink:label="ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesPropertyPlantAndEquipment" xlink:title="ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesPropertyPlantAndEquipment"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:to="ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesPropertyPlantAndEquipment" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems to ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesPropertyPlantAndEquipment" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_IncreaseDecreaseThroughTransfersPropertyPlantAndEquipment" xlink:label="ifrs-full_IncreaseDecreaseThroughTransfersPropertyPlantAndEquipment" xlink:title="ifrs-full_IncreaseDecreaseThroughTransfersPropertyPlantAndEquipment"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:to="ifrs-full_IncreaseDecreaseThroughTransfersPropertyPlantAndEquipment" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems to ifrs-full_IncreaseDecreaseThroughTransfersPropertyPlantAndEquipment" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PropertyPlantAndEquipment" xlink:label="ifrs-full_PropertyPlantAndEquipment" xlink:title="ifrs-full_PropertyPlantAndEquipment"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:to="ifrs-full_PropertyPlantAndEquipment" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems to ifrs-full_PropertyPlantAndEquipment" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IncreasedecreaseThroughDiscontinuedOperationPropertyPlantAndEquipment" xlink:label="csan_IncreasedecreaseThroughDiscontinuedOperationPropertyPlantAndEquipment" xlink:title="csan_IncreasedecreaseThroughDiscontinuedOperationPropertyPlantAndEquipment"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:to="csan_IncreasedecreaseThroughDiscontinuedOperationPropertyPlantAndEquipment" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems to csan_IncreasedecreaseThroughDiscontinuedOperationPropertyPlantAndEquipment" xlink:type="arc" use="optional" order="8" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/PropertyplantandequipmentintangibleassetsgoodwillrightofuseassetsandcontractassetsScheduleofPropertyPlantandEquipmentParentheticalDetail">
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:label="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:title="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BankLoanGuarantee" xlink:label="csan_BankLoanGuarantee" xlink:title="csan_BankLoanGuarantee"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:to="csan_BankLoanGuarantee" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems to csan_BankLoanGuarantee" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:label="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:title="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:to="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems to ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:label="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:title="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:to="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable to ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PropertyPlantAndEquipmentMember" xlink:label="ifrs-full_PropertyPlantAndEquipmentMember" xlink:title="ifrs-full_PropertyPlantAndEquipmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:to="ifrs-full_PropertyPlantAndEquipmentMember" xlink:title="Definition : ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis to ifrs-full_PropertyPlantAndEquipmentMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_WagonsAndLocomotivesMember" xlink:label="csan_WagonsAndLocomotivesMember" xlink:title="csan_WagonsAndLocomotivesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_PropertyPlantAndEquipmentMember" xlink:to="csan_WagonsAndLocomotivesMember" xlink:title="Definition : ifrs-full_PropertyPlantAndEquipmentMember to csan_WagonsAndLocomotivesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PropertyPlantAndEquipmentMember" xlink:label="ifrs-full_PropertyPlantAndEquipmentMember_1" xlink:title="ifrs-full_PropertyPlantAndEquipmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis" xlink:to="ifrs-full_PropertyPlantAndEquipmentMember_1" xlink:title="Definition : ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis to ifrs-full_PropertyPlantAndEquipmentMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NewIFRSsAxis" xlink:label="ifrs-full_NewIFRSsAxis" xlink:title="ifrs-full_NewIFRSsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:to="ifrs-full_NewIFRSsAxis" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable to ifrs-full_NewIFRSsAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NewIFRSsMember" xlink:label="ifrs-full_NewIFRSsMember" xlink:title="ifrs-full_NewIFRSsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_NewIFRSsAxis" xlink:to="ifrs-full_NewIFRSsMember" xlink:title="Definition : ifrs-full_NewIFRSsAxis to ifrs-full_NewIFRSsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IfrsSixteenMember" xlink:label="csan_IfrsSixteenMember" xlink:title="csan_IfrsSixteenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_NewIFRSsMember" xlink:to="csan_IfrsSixteenMember" xlink:title="Definition : ifrs-full_NewIFRSsMember to csan_IfrsSixteenMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NewIFRSsMember" xlink:label="ifrs-full_NewIFRSsMember_1" xlink:title="ifrs-full_NewIFRSsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_NewIFRSsAxis" xlink:to="ifrs-full_NewIFRSsMember_1" xlink:title="Definition : ifrs-full_NewIFRSsAxis to ifrs-full_NewIFRSsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:label="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:title="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable" xlink:to="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentTable to ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CarryingAmountMember" xlink:label="ifrs-full_CarryingAmountMember" xlink:title="ifrs-full_CarryingAmountMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:to="ifrs-full_CarryingAmountMember" xlink:title="Definition : ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis to ifrs-full_CarryingAmountMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GrossCarryingAmountMember" xlink:label="ifrs-full_GrossCarryingAmountMember" xlink:title="ifrs-full_GrossCarryingAmountMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_CarryingAmountMember" xlink:to="ifrs-full_GrossCarryingAmountMember" xlink:title="Definition : ifrs-full_CarryingAmountMember to ifrs-full_GrossCarryingAmountMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_AccumulatedDepreciationAndAmortisationMember" xlink:label="ifrs-full_AccumulatedDepreciationAndAmortisationMember" xlink:title="ifrs-full_AccumulatedDepreciationAndAmortisationMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_CarryingAmountMember" xlink:to="ifrs-full_AccumulatedDepreciationAndAmortisationMember" xlink:title="Definition : ifrs-full_CarryingAmountMember to ifrs-full_AccumulatedDepreciationAndAmortisationMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CarryingAmountMember" xlink:label="ifrs-full_CarryingAmountMember_1" xlink:title="ifrs-full_CarryingAmountMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:to="ifrs-full_CarryingAmountMember_1" xlink:title="Definition : ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis to ifrs-full_CarryingAmountMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IncreasedecreaseThroughTransfersFromtoRightOfUseAssets" xlink:label="csan_IncreasedecreaseThroughTransfersFromtoRightOfUseAssets" xlink:title="csan_IncreasedecreaseThroughTransfersFromtoRightOfUseAssets"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:to="csan_IncreasedecreaseThroughTransfersFromtoRightOfUseAssets" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems to csan_IncreasedecreaseThroughTransfersFromtoRightOfUseAssets" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
</link:definitionLink>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfAssetsAxis" xlink:label="ifrs-full_ClassesOfAssetsAxis" xlink:title="ifrs-full_ClassesOfAssetsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable" xlink:to="ifrs-full_ClassesOfAssetsAxis" xlink:title="Definition : ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable to ifrs-full_ClassesOfAssetsAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfAssetsMember" xlink:label="ifrs-full_ClassesOfAssetsMember" xlink:title="ifrs-full_ClassesOfAssetsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfAssetsAxis" xlink:to="ifrs-full_ClassesOfAssetsMember" xlink:title="Definition : ifrs-full_ClassesOfAssetsAxis to ifrs-full_ClassesOfAssetsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_LandAndBuildingsMember" xlink:label="ifrs-full_LandAndBuildingsMember" xlink:title="ifrs-full_LandAndBuildingsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfAssetsMember" xlink:to="ifrs-full_LandAndBuildingsMember" xlink:title="Definition : ifrs-full_ClassesOfAssetsMember to ifrs-full_LandAndBuildingsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_MachineryEquipmentAndFacilitiesMember" xlink:label="csan_MachineryEquipmentAndFacilitiesMember" xlink:title="csan_MachineryEquipmentAndFacilitiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfAssetsMember" xlink:to="csan_MachineryEquipmentAndFacilitiesMember" xlink:title="Definition : ifrs-full_ClassesOfAssetsMember to csan_MachineryEquipmentAndFacilitiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_FreightCarsAndLocomotivesMember" xlink:label="csan_FreightCarsAndLocomotivesMember" xlink:title="csan_FreightCarsAndLocomotivesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfAssetsMember" xlink:to="csan_FreightCarsAndLocomotivesMember" xlink:title="Definition : ifrs-full_ClassesOfAssetsMember to csan_FreightCarsAndLocomotivesMember" xlink:type="arc" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SoftwareMember" xlink:label="csan_SoftwareMember" xlink:title="csan_SoftwareMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfAssetsMember" xlink:to="csan_SoftwareMember" xlink:title="Definition : ifrs-full_ClassesOfAssetsMember to csan_SoftwareMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_VehiclesMember" xlink:label="ifrs-full_VehiclesMember" xlink:title="ifrs-full_VehiclesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfAssetsMember" xlink:to="ifrs-full_VehiclesMember" xlink:title="Definition : ifrs-full_ClassesOfAssetsMember to ifrs-full_VehiclesMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PortAndRailInfrastructureMember" xlink:label="csan_PortAndRailInfrastructureMember" xlink:title="csan_PortAndRailInfrastructureMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfAssetsMember" xlink:to="csan_PortAndRailInfrastructureMember" xlink:title="Definition : ifrs-full_ClassesOfAssetsMember to csan_PortAndRailInfrastructureMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfAssetsMember" xlink:label="ifrs-full_ClassesOfAssetsMember_1" xlink:title="ifrs-full_ClassesOfAssetsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfAssetsAxis" xlink:to="ifrs-full_ClassesOfAssetsMember_1" xlink:title="Definition : ifrs-full_ClassesOfAssetsAxis to ifrs-full_ClassesOfAssetsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:label="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:title="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable" xlink:to="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:title="Definition : ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable to ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CarryingAmountMember" xlink:label="ifrs-full_CarryingAmountMember" xlink:title="ifrs-full_CarryingAmountMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:to="ifrs-full_CarryingAmountMember" xlink:title="Definition : ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis to ifrs-full_CarryingAmountMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GrossCarryingAmountMember" xlink:label="ifrs-full_GrossCarryingAmountMember" xlink:title="ifrs-full_GrossCarryingAmountMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_CarryingAmountMember" xlink:to="ifrs-full_GrossCarryingAmountMember" xlink:title="Definition : ifrs-full_CarryingAmountMember to ifrs-full_GrossCarryingAmountMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_AccumulatedDepreciationAndAmortisationMember" xlink:label="ifrs-full_AccumulatedDepreciationAndAmortisationMember" xlink:title="ifrs-full_AccumulatedDepreciationAndAmortisationMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_CarryingAmountMember" xlink:to="ifrs-full_AccumulatedDepreciationAndAmortisationMember" xlink:title="Definition : ifrs-full_CarryingAmountMember to ifrs-full_AccumulatedDepreciationAndAmortisationMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CarryingAmountMember" xlink:label="ifrs-full_CarryingAmountMember_1" xlink:title="ifrs-full_CarryingAmountMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis" xlink:to="ifrs-full_CarryingAmountMember_1" xlink:title="Definition : ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis to ifrs-full_CarryingAmountMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable" xlink:label="ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable" xlink:title="ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:to="ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems to ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable" xlink:type="arc" use="optional" order="0" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfAssetsAxis" xlink:label="ifrs-full_ClassesOfAssetsAxis" xlink:title="ifrs-full_ClassesOfAssetsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable" xlink:to="ifrs-full_ClassesOfAssetsAxis" xlink:title="Definition : ifrs-full_DisclosureOfQuantitativeInformationAboutRightofuseAssetsTable to ifrs-full_ClassesOfAssetsAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfAssetsMember" xlink:label="ifrs-full_ClassesOfAssetsMember" xlink:title="ifrs-full_ClassesOfAssetsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfAssetsAxis" xlink:to="ifrs-full_ClassesOfAssetsMember" xlink:title="Definition : ifrs-full_ClassesOfAssetsAxis to ifrs-full_ClassesOfAssetsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PropertyPlantAndEquipmentMember" xlink:label="ifrs-full_PropertyPlantAndEquipmentMember" xlink:title="ifrs-full_PropertyPlantAndEquipmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfAssetsMember" xlink:to="ifrs-full_PropertyPlantAndEquipmentMember" xlink:title="Definition : ifrs-full_ClassesOfAssetsMember to ifrs-full_PropertyPlantAndEquipmentMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_OtherAssetsMember" xlink:label="ifrs-full_OtherAssetsMember" xlink:title="ifrs-full_OtherAssetsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfAssetsMember" xlink:to="ifrs-full_OtherAssetsMember" xlink:title="Definition : ifrs-full_ClassesOfAssetsMember to ifrs-full_OtherAssetsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfAssetsMember" xlink:label="ifrs-full_ClassesOfAssetsMember_1" xlink:title="ifrs-full_ClassesOfAssetsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfAssetsAxis" xlink:to="ifrs-full_ClassesOfAssetsMember_1" xlink:title="Definition : ifrs-full_ClassesOfAssetsAxis to ifrs-full_ClassesOfAssetsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems" xlink:to="csan_IncreasedecreaseThroughTransfersFromtoPropertyPlantAndEquipmentAndOtherAssets" xlink:title="Definition : ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems to csan_IncreasedecreaseThroughTransfersFromtoPropertyPlantAndEquipmentAndOtherAssets" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/ConcessionsPayableSummaryOfConcessionsPayableDetail">
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:label="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:title="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable" xlink:label="csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable" xlink:title="csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:to="csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems to csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable" xlink:type="arc" use="optional" order="0" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfLiabilitiesAxis" xlink:label="ifrs-full_ClassesOfLiabilitiesAxis" xlink:title="ifrs-full_ClassesOfLiabilitiesAxis"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_LiabilitiesMember" xlink:label="ifrs-full_LiabilitiesMember" xlink:title="ifrs-full_LiabilitiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfLiabilitiesAxis" xlink:to="ifrs-full_LiabilitiesMember" xlink:title="Definition : ifrs-full_ClassesOfLiabilitiesAxis to ifrs-full_LiabilitiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CourtDiscussionMember" xlink:label="csan_CourtDiscussionMember" xlink:title="csan_CourtDiscussionMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_LiabilitiesMember" xlink:to="csan_CourtDiscussionMember" xlink:title="Definition : ifrs-full_LiabilitiesMember to csan_CourtDiscussionMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RailroadConcessionPayableUnderLitigationMember" xlink:label="csan_RailroadConcessionPayableUnderLitigationMember" xlink:title="csan_RailroadConcessionPayableUnderLitigationMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_LiabilitiesMember" xlink:to="csan_RailroadConcessionPayableUnderLitigationMember" xlink:title="Definition : ifrs-full_LiabilitiesMember to csan_RailroadConcessionPayableUnderLitigationMember" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OtherConcessionsPayableMember" xlink:label="csan_OtherConcessionsPayableMember" xlink:title="csan_OtherConcessionsPayableMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_LiabilitiesMember" xlink:to="csan_OtherConcessionsPayableMember" xlink:title="Definition : ifrs-full_LiabilitiesMember to csan_OtherConcessionsPayableMember" xlink:type="arc" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ConcessionsPayableMember" xlink:label="csan_ConcessionsPayableMember" xlink:title="csan_ConcessionsPayableMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_LiabilitiesMember" xlink:to="csan_ConcessionsPayableMember" xlink:title="Definition : ifrs-full_LiabilitiesMember to csan_ConcessionsPayableMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LeasesAndConcessionsPayableMember" xlink:label="csan_LeasesAndConcessionsPayableMember" xlink:title="csan_LeasesAndConcessionsPayableMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_LiabilitiesMember" xlink:to="csan_LeasesAndConcessionsPayableMember" xlink:title="Definition : ifrs-full_LiabilitiesMember to csan_LeasesAndConcessionsPayableMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_LiabilitiesMember" xlink:label="ifrs-full_LiabilitiesMember_1" xlink:title="ifrs-full_LiabilitiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfLiabilitiesAxis" xlink:to="ifrs-full_LiabilitiesMember_1" xlink:title="Definition : ifrs-full_ClassesOfLiabilitiesAxis to ifrs-full_LiabilitiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:label="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="ifrs-full_SignificantInvestmentsInSubsidiariesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable" xlink:to="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable to ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoMalhaPaulistaSAMember" xlink:label="csan_RumoMalhaPaulistaSAMember" xlink:title="csan_RumoMalhaPaulistaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoMalhaPaulistaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoMalhaPaulistaSAMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoMalhaOesteSAMember" xlink:label="csan_RumoMalhaOesteSAMember" xlink:title="csan_RumoMalhaOesteSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoMalhaOesteSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoMalhaOesteSAMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoMalhaSulSAMember" xlink:label="csan_RumoMalhaSulSAMember" xlink:title="csan_RumoMalhaSulSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoMalhaSulSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoMalhaSulSAMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ConcessionsPayables" xlink:label="csan_ConcessionsPayables" xlink:title="csan_ConcessionsPayables"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:to="csan_ConcessionsPayables" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems to csan_ConcessionsPayables" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CurrentConcessionsPayables" xlink:label="csan_CurrentConcessionsPayables" xlink:title="csan_CurrentConcessionsPayables"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:to="csan_CurrentConcessionsPayables" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems to csan_CurrentConcessionsPayables" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_NoncurrentConcessionsPayables" xlink:label="csan_NoncurrentConcessionsPayables" xlink:title="csan_NoncurrentConcessionsPayables"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:to="csan_NoncurrentConcessionsPayables" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems to csan_NoncurrentConcessionsPayables" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LeasePayable" xlink:label="csan_LeasePayable" xlink:title="csan_LeasePayable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:to="csan_LeasePayable" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems to csan_LeasePayable" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LeasesAndConcessionsPayable" xlink:label="csan_LeasesAndConcessionsPayable" xlink:title="csan_LeasesAndConcessionsPayable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:to="csan_LeasesAndConcessionsPayable" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems to csan_LeasesAndConcessionsPayable" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/ConcessionsPayableAdditionalInformationDetail">
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:label="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:title="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable" xlink:label="csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable" xlink:title="csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:to="csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems to csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable" xlink:type="arc" use="optional" order="0" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfLiabilitiesAxis" xlink:label="ifrs-full_ClassesOfLiabilitiesAxis" xlink:title="ifrs-full_ClassesOfLiabilitiesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable" xlink:to="ifrs-full_ClassesOfLiabilitiesAxis" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable to ifrs-full_ClassesOfLiabilitiesAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_LiabilitiesMember" xlink:label="ifrs-full_LiabilitiesMember" xlink:title="ifrs-full_LiabilitiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfLiabilitiesAxis" xlink:to="ifrs-full_LiabilitiesMember" xlink:title="Definition : ifrs-full_ClassesOfLiabilitiesAxis to ifrs-full_LiabilitiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RailroadConcessionPayableUnderLitigationMember" xlink:label="csan_RailroadConcessionPayableUnderLitigationMember" xlink:title="csan_RailroadConcessionPayableUnderLitigationMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_LiabilitiesMember" xlink:to="csan_RailroadConcessionPayableUnderLitigationMember" xlink:title="Definition : ifrs-full_LiabilitiesMember to csan_RailroadConcessionPayableUnderLitigationMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_LiabilitiesMember" xlink:label="ifrs-full_LiabilitiesMember_1" xlink:title="ifrs-full_LiabilitiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfLiabilitiesAxis" xlink:to="ifrs-full_LiabilitiesMember_1" xlink:title="Definition : ifrs-full_ClassesOfLiabilitiesAxis to ifrs-full_LiabilitiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:label="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:title="ifrs-full_CategoriesOfRelatedPartiesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable" xlink:to="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable to ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:label="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:title="ifrs-full_EntitysTotalForRelatedPartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:to="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:title="Definition : ifrs-full_CategoriesOfRelatedPartiesAxis to ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoSAMember" xlink:label="csan_RumoSAMember" xlink:title="csan_RumoSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_RumoSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_RumoSAMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ComgasMember" xlink:label="csan_ComgasMember" xlink:title="csan_ComgasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_ComgasMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_ComgasMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:label="ifrs-full_EntitysTotalForRelatedPartiesMember_1" xlink:title="ifrs-full_EntitysTotalForRelatedPartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:to="ifrs-full_EntitysTotalForRelatedPartiesMember_1" xlink:title="Definition : ifrs-full_CategoriesOfRelatedPartiesAxis to ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GainsOnLitigationSettlements" xlink:label="ifrs-full_GainsOnLitigationSettlements" xlink:title="ifrs-full_GainsOnLitigationSettlements"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:to="ifrs-full_GainsOnLitigationSettlements" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems to ifrs-full_GainsOnLitigationSettlements" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_GainOnReversalOfLeaseLiabilitiesRelatedToOtherIncomeExpenses" xlink:label="csan_GainOnReversalOfLeaseLiabilitiesRelatedToOtherIncomeExpenses" xlink:title="csan_GainOnReversalOfLeaseLiabilitiesRelatedToOtherIncomeExpenses"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:to="csan_GainOnReversalOfLeaseLiabilitiesRelatedToOtherIncomeExpenses" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems to csan_GainOnReversalOfLeaseLiabilitiesRelatedToOtherIncomeExpenses" xlink:type="arc" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_GainOnReversalOfLeaseLiabilitiesRelatedToFinancialResult" xlink:label="csan_GainOnReversalOfLeaseLiabilitiesRelatedToFinancialResult" xlink:title="csan_GainOnReversalOfLeaseLiabilitiesRelatedToFinancialResult"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:to="csan_GainOnReversalOfLeaseLiabilitiesRelatedToFinancialResult" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems to csan_GainOnReversalOfLeaseLiabilitiesRelatedToFinancialResult" xlink:type="arc" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DescriptionOfLifeAndOtherSignificantTermsOfArrangementInvolvingLegalFormOfLease2019" xlink:label="csan_DescriptionOfLifeAndOtherSignificantTermsOfArrangementInvolvingLegalFormOfLease2019" xlink:title="csan_DescriptionOfLifeAndOtherSignificantTermsOfArrangementInvolvingLegalFormOfLease2019"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:to="csan_DescriptionOfLifeAndOtherSignificantTermsOfArrangementInvolvingLegalFormOfLease2019" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems to csan_DescriptionOfLifeAndOtherSignificantTermsOfArrangementInvolvingLegalFormOfLease2019" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_FinancialCommitmentEstimatedPresentValue" xlink:label="csan_FinancialCommitmentEstimatedPresentValue" xlink:title="csan_FinancialCommitmentEstimatedPresentValue"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:to="csan_FinancialCommitmentEstimatedPresentValue" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems to csan_FinancialCommitmentEstimatedPresentValue" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/ConcessionsPayableSummaryOfJudicialDepositsDetail">
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfJudicialDepositsLineItems" xlink:label="csan_DisclosureOfJudicialDepositsLineItems" xlink:title="csan_DisclosureOfJudicialDepositsLineItems"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfJudicialDepositsTable" xlink:label="csan_DisclosureOfJudicialDepositsTable" xlink:title="csan_DisclosureOfJudicialDepositsTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="csan_DisclosureOfJudicialDepositsLineItems" xlink:to="csan_DisclosureOfJudicialDepositsTable" xlink:title="Definition : csan_DisclosureOfJudicialDepositsLineItems to csan_DisclosureOfJudicialDepositsTable" xlink:type="arc" use="optional" order="0" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:label="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="ifrs-full_SignificantInvestmentsInSubsidiariesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfJudicialDepositsTable" xlink:to="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="Definition : csan_DisclosureOfJudicialDepositsTable to ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoMalhaPaulistaMember" xlink:label="csan_RumoMalhaPaulistaMember" xlink:title="csan_RumoMalhaPaulistaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoMalhaPaulistaMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoMalhaPaulistaMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoMalhaOesteMember" xlink:label="csan_RumoMalhaOesteMember" xlink:title="csan_RumoMalhaOesteMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoMalhaOesteMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoMalhaOesteMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_JudicialDeposits" xlink:label="csan_JudicialDeposits" xlink:title="csan_JudicialDeposits"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfJudicialDepositsLineItems" xlink:to="csan_JudicialDeposits" xlink:title="Definition : csan_DisclosureOfJudicialDepositsLineItems to csan_JudicialDeposits" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/ConcessionsPayableSummaryOfRegulatoryAssetsLiabilitiesDetail">
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfInformationAboutAmountsRecognisedInRelationToRegulatoryDeferralAccountBalancesLineItems" xlink:label="ifrs-full_DisclosureOfInformationAboutAmountsRecognisedInRelationToRegulatoryDeferralAccountBalancesLineItems" xlink:title="ifrs-full_DisclosureOfInformationAboutAmountsRecognisedInRelationToRegulatoryDeferralAccountBalancesLineItems"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CostOfGasToBeRecoveredTransferred" xlink:label="csan_CostOfGasToBeRecoveredTransferred" xlink:title="csan_CostOfGasToBeRecoveredTransferred"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfInformationAboutAmountsRecognisedInRelationToRegulatoryDeferralAccountBalancesLineItems" xlink:to="csan_CostOfGasToBeRecoveredTransferred" xlink:title="Definition : ifrs-full_DisclosureOfInformationAboutAmountsRecognisedInRelationToRegulatoryDeferralAccountBalancesLineItems to csan_CostOfGasToBeRecoveredTransferred" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CreditsOfTaxesToBeRecoveredTransferred" xlink:label="csan_CreditsOfTaxesToBeRecoveredTransferred" xlink:title="csan_CreditsOfTaxesToBeRecoveredTransferred"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfInformationAboutAmountsRecognisedInRelationToRegulatoryDeferralAccountBalancesLineItems" xlink:to="csan_CreditsOfTaxesToBeRecoveredTransferred" xlink:title="Definition : ifrs-full_DisclosureOfInformationAboutAmountsRecognisedInRelationToRegulatoryDeferralAccountBalancesLineItems to csan_CreditsOfTaxesToBeRecoveredTransferred" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_LitigationCaseTypeDomain" xlink:label="srt_LitigationCaseTypeDomain_1" xlink:title="srt_LitigationCaseTypeDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_LitigationCaseAxis" xlink:to="srt_LitigationCaseTypeDomain_1" xlink:title="Definition : srt_LitigationCaseAxis to srt_LitigationCaseTypeDomain" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_FederalAndProvincialIncomeTaxRate" xlink:label="csan_FederalAndProvincialIncomeTaxRate" xlink:title="csan_FederalAndProvincialIncomeTaxRate"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOtherProvisionsLineItems" xlink:to="csan_FederalAndProvincialIncomeTaxRate" xlink:title="Definition : ifrs-full_DisclosureOfOtherProvisionsLineItems to csan_FederalAndProvincialIncomeTaxRate" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IsolatedFineRateOfAcquiredAssets" xlink:label="csan_IsolatedFineRateOfAcquiredAssets" xlink:title="csan_IsolatedFineRateOfAcquiredAssets"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOtherProvisionsLineItems" xlink:to="csan_IsolatedFineRateOfAcquiredAssets" xlink:title="Definition : ifrs-full_DisclosureOfOtherProvisionsLineItems to csan_IsolatedFineRateOfAcquiredAssets" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SocialSecurityPercentage" xlink:label="csan_SocialSecurityPercentage" xlink:title="csan_SocialSecurityPercentage"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOtherProvisionsLineItems" xlink:to="csan_SocialSecurityPercentage" xlink:title="Definition : ifrs-full_DisclosureOfOtherProvisionsLineItems to csan_SocialSecurityPercentage" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NewProvisionsOtherProvisions" xlink:label="ifrs-full_NewProvisionsOtherProvisions" xlink:title="ifrs-full_NewProvisionsOtherProvisions"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOtherProvisionsLineItems" xlink:to="ifrs-full_NewProvisionsOtherProvisions" xlink:title="Definition : ifrs-full_DisclosureOfOtherProvisionsLineItems to ifrs-full_NewProvisionsOtherProvisions" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_LongtermLegalProceedingsProvision" xlink:label="ifrs-full_LongtermLegalProceedingsProvision" xlink:title="ifrs-full_LongtermLegalProceedingsProvision"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOtherProvisionsLineItems" xlink:to="ifrs-full_LongtermLegalProceedingsProvision" xlink:title="Definition : ifrs-full_DisclosureOfOtherProvisionsLineItems to ifrs-full_LongtermLegalProceedingsProvision" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_MandatoryJudicialDepositsForLegalProceeding" xlink:label="csan_MandatoryJudicialDepositsForLegalProceeding" xlink:title="csan_MandatoryJudicialDepositsForLegalProceeding"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfOtherProvisionsLineItems" xlink:to="csan_MandatoryJudicialDepositsForLegalProceeding" xlink:title="Definition : ifrs-full_DisclosureOfOtherProvisionsLineItems to csan_MandatoryJudicialDepositsForLegalProceeding" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfContingentLiabilitiesLineItems" xlink:label="ifrs-full_DisclosureOfContingentLiabilitiesLineItems" xlink:title="ifrs-full_DisclosureOfContingentLiabilitiesLineItems"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfContingentLiabilitiesTable" xlink:label="ifrs-full_DisclosureOfContingentLiabilitiesTable" xlink:title="ifrs-full_DisclosureOfContingentLiabilitiesTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ifrs-full_DisclosureOfContingentLiabilitiesLineItems" xlink:to="ifrs-full_DisclosureOfContingentLiabilitiesTable" xlink:title="Definition : ifrs-full_DisclosureOfContingentLiabilitiesLineItems to ifrs-full_DisclosureOfContingentLiabilitiesTable" xlink:type="arc" use="optional" order="0" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CategoriesOfContingentLiabilitiesAxis" xlink:label="csan_CategoriesOfContingentLiabilitiesAxis" xlink:title="csan_CategoriesOfContingentLiabilitiesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfContingentLiabilitiesTable" xlink:to="csan_CategoriesOfContingentLiabilitiesAxis" xlink:title="Definition : ifrs-full_DisclosureOfContingentLiabilitiesTable to csan_CategoriesOfContingentLiabilitiesAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CategoriesOfContingentLiabilitiesDomain" xlink:label="csan_CategoriesOfContingentLiabilitiesDomain" xlink:title="csan_CategoriesOfContingentLiabilitiesDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="csan_CategoriesOfContingentLiabilitiesAxis" xlink:to="csan_CategoriesOfContingentLiabilitiesDomain" xlink:title="Definition : csan_CategoriesOfContingentLiabilitiesAxis to csan_CategoriesOfContingentLiabilitiesDomain" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LegalProceedingsContingentLiabilityCivilRegulatoryAndEnvironmentalMember" xlink:label="csan_LegalProceedingsContingentLiabilityCivilRegulatoryAndEnvironmentalMember" xlink:title="csan_LegalProceedingsContingentLiabilityCivilRegulatoryAndEnvironmentalMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_CategoriesOfContingentLiabilitiesDomain" xlink:to="csan_LegalProceedingsContingentLiabilityCivilRegulatoryAndEnvironmentalMember" xlink:title="Definition : csan_CategoriesOfContingentLiabilitiesDomain to csan_LegalProceedingsContingentLiabilityCivilRegulatoryAndEnvironmentalMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CategoriesOfContingentLiabilitiesDomain" xlink:label="csan_CategoriesOfContingentLiabilitiesDomain_1" xlink:title="csan_CategoriesOfContingentLiabilitiesDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="csan_CategoriesOfContingentLiabilitiesAxis" xlink:to="csan_CategoriesOfContingentLiabilitiesDomain_1" xlink:title="Definition : csan_CategoriesOfContingentLiabilitiesAxis to csan_CategoriesOfContingentLiabilitiesDomain" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfContingentLiabilitiesAxis" xlink:label="ifrs-full_ClassesOfContingentLiabilitiesAxis" xlink:title="ifrs-full_ClassesOfContingentLiabilitiesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfContingentLiabilitiesTable" xlink:to="ifrs-full_ClassesOfContingentLiabilitiesAxis" xlink:title="Definition : ifrs-full_DisclosureOfContingentLiabilitiesTable to ifrs-full_ClassesOfContingentLiabilitiesAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ContingentLiabilitiesMember" xlink:label="ifrs-full_ContingentLiabilitiesMember" xlink:title="ifrs-full_ContingentLiabilitiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfContingentLiabilitiesAxis" xlink:to="ifrs-full_ContingentLiabilitiesMember" xlink:title="Definition : ifrs-full_ClassesOfContingentLiabilitiesAxis to ifrs-full_ContingentLiabilitiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LegalProceedingsContingentLiabilityTaxMember" xlink:label="csan_LegalProceedingsContingentLiabilityTaxMember" xlink:title="csan_LegalProceedingsContingentLiabilityTaxMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ContingentLiabilitiesMember" xlink:to="csan_LegalProceedingsContingentLiabilityTaxMember" xlink:title="Definition : ifrs-full_ContingentLiabilitiesMember to csan_LegalProceedingsContingentLiabilityTaxMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ContingentLiabilitiesMember" xlink:label="ifrs-full_ContingentLiabilitiesMember_1" xlink:title="ifrs-full_ContingentLiabilitiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfContingentLiabilitiesAxis" xlink:to="ifrs-full_ContingentLiabilitiesMember_1" xlink:title="Definition : ifrs-full_ClassesOfContingentLiabilitiesAxis to ifrs-full_ContingentLiabilitiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfContingentLiabilitiesTable" xlink:to="csan_LitigationCase1Axis" xlink:title="Definition : ifrs-full_DisclosureOfContingentLiabilitiesTable to csan_LitigationCase1Axis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LitigationCase1Member" xlink:label="csan_LitigationCase1Member" xlink:title="csan_LitigationCase1Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="csan_LitigationCase1Axis" xlink:to="csan_LitigationCase1Member" xlink:title="Definition : csan_LitigationCase1Axis to csan_LitigationCase1Member" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CivilMember" xlink:label="csan_CivilMember" xlink:title="csan_CivilMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_CivilMember" xlink:title="Definition : csan_LitigationCase1Member to csan_CivilMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CompensationWithIpiIn6798Member" xlink:label="csan_CompensationWithIpiIn6798Member" xlink:title="csan_CompensationWithIpiIn6798Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_CompensationWithIpiIn6798Member" xlink:title="Definition : csan_LitigationCase1Member to csan_CompensationWithIpiIn6798Member" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_EnvironmentalMember" xlink:label="csan_EnvironmentalMember" xlink:title="csan_EnvironmentalMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_EnvironmentalMember" xlink:title="Definition : csan_LitigationCase1Member to csan_EnvironmentalMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_FederalIncomeTaxesMember" xlink:label="csan_FederalIncomeTaxesMember" xlink:title="csan_FederalIncomeTaxesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_FederalIncomeTaxesMember" xlink:title="Definition : csan_LitigationCase1Member to csan_FederalIncomeTaxesMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_FinancialTransactionsTaxOnLoanMember" xlink:label="csan_FinancialTransactionsTaxOnLoanMember" xlink:title="csan_FinancialTransactionsTaxOnLoanMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_FinancialTransactionsTaxOnLoanMember" xlink:title="Definition : csan_LitigationCase1Member to csan_FinancialTransactionsTaxOnLoanMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ForeignFinancialOperationMember" xlink:label="csan_ForeignFinancialOperationMember" xlink:title="csan_ForeignFinancialOperationMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_ForeignFinancialOperationMember" xlink:title="Definition : csan_LitigationCase1Member to csan_ForeignFinancialOperationMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_GoodwillRumoMember" xlink:label="csan_GoodwillRumoMember" xlink:title="csan_GoodwillRumoMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_GoodwillRumoMember" xlink:title="Definition : csan_LitigationCase1Member to csan_GoodwillRumoMember" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IcmsStateVatMember" xlink:label="csan_IcmsStateVatMember" xlink:title="csan_IcmsStateVatMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_IcmsStateVatMember" xlink:title="Definition : csan_LitigationCase1Member to csan_IcmsStateVatMember" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_InssSocialSecurityAndOtherMember" xlink:label="csan_InssSocialSecurityAndOtherMember" xlink:title="csan_InssSocialSecurityAndOtherMember"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IpiExciseTaxCreditNtMember" xlink:label="csan_IpiExciseTaxCreditNtMember" xlink:title="csan_IpiExciseTaxCreditNtMember"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IrrfWithholdingTaxMember" xlink:label="csan_IrrfWithholdingTaxMember" xlink:title="csan_IrrfWithholdingTaxMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_IrrfWithholdingTaxMember" xlink:title="Definition : csan_LitigationCase1Member to csan_IrrfWithholdingTaxMember" xlink:type="arc" use="optional" order="10" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LaborMember" xlink:label="csan_LaborMember" xlink:title="csan_LaborMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_LaborMember" xlink:title="Definition : csan_LitigationCase1Member to csan_LaborMember" xlink:type="arc" use="optional" order="11" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_Mp470TaxInstallmentsMember" xlink:label="csan_Mp470TaxInstallmentsMember" xlink:title="csan_Mp470TaxInstallmentsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_Mp470TaxInstallmentsMember" xlink:title="Definition : csan_LitigationCase1Member to csan_Mp470TaxInstallmentsMember" xlink:type="arc" use="optional" order="12" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OtherClaimsMember" xlink:label="csan_OtherClaimsMember" xlink:title="csan_OtherClaimsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_OtherClaimsMember" xlink:title="Definition : csan_LitigationCase1Member to csan_OtherClaimsMember" xlink:type="arc" use="optional" order="13" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PenaltiesRelatedToTaxPositionsMember" xlink:label="csan_PenaltiesRelatedToTaxPositionsMember" xlink:title="csan_PenaltiesRelatedToTaxPositionsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_PenaltiesRelatedToTaxPositionsMember" xlink:title="Definition : csan_LitigationCase1Member to csan_PenaltiesRelatedToTaxPositionsMember" xlink:type="arc" use="optional" order="14" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PisAndCofinsRevenueTaxesMember" xlink:label="csan_PisAndCofinsRevenueTaxesMember" xlink:title="csan_PisAndCofinsRevenueTaxesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_PisAndCofinsRevenueTaxesMember" xlink:title="Definition : csan_LitigationCase1Member to csan_PisAndCofinsRevenueTaxesMember" xlink:type="arc" use="optional" order="15" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RegulatoryMember" xlink:label="csan_RegulatoryMember" xlink:title="csan_RegulatoryMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_RegulatoryMember" xlink:title="Definition : csan_LitigationCase1Member to csan_RegulatoryMember" xlink:type="arc" use="optional" order="16" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_StockOptionClaimsMember" xlink:label="csan_StockOptionClaimsMember" xlink:title="csan_StockOptionClaimsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_StockOptionClaimsMember" xlink:title="Definition : csan_LitigationCase1Member to csan_StockOptionClaimsMember" xlink:type="arc" use="optional" order="17" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_TaxMember" xlink:label="csan_TaxMember" xlink:title="csan_TaxMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_LitigationCase1Member" xlink:to="csan_TaxMember" xlink:title="Definition : csan_LitigationCase1Member to csan_TaxMember" xlink:type="arc" use="optional" order="18" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LitigationCase1Member" xlink:label="csan_LitigationCase1Member_1" xlink:title="csan_LitigationCase1Member"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EquityMember" xlink:to="csan_AccumulatedOtherComprehensiveGainOnCashFlowHedgeInJointVenturesMember" xlink:title="Definition : ifrs-full_EquityMember to csan_AccumulatedOtherComprehensiveGainOnCashFlowHedgeInJointVenturesMember" xlink:type="arc" use="optional" order="8" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EquityMember" xlink:to="csan_AccumulatedOtherComprehensiveIncomeGainLossOnCashFlowHedgeMember" xlink:title="Definition : ifrs-full_EquityMember to csan_AccumulatedOtherComprehensiveIncomeGainLossOnCashFlowHedgeMember" xlink:type="arc" order="9" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ComponentsOfEquityAxis" xlink:to="ifrs-full_EquityMember_1" xlink:title="Definition : ifrs-full_ComponentsOfEquityAxis to ifrs-full_EquityMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_Equity" xlink:label="ifrs-full_Equity" xlink:title="ifrs-full_Equity"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfAnalysisOfOtherComprehensiveIncomeByItemLineItems" xlink:to="ifrs-full_Equity" xlink:title="Definition : ifrs-full_DisclosureOfAnalysisOfOtherComprehensiveIncomeByItemLineItems to ifrs-full_Equity" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_OtherComprehensiveIncome" xlink:label="ifrs-full_OtherComprehensiveIncome" xlink:title="ifrs-full_OtherComprehensiveIncome"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfAnalysisOfOtherComprehensiveIncomeByItemLineItems" xlink:to="ifrs-full_OtherComprehensiveIncome" xlink:title="Definition : ifrs-full_DisclosureOfAnalysisOfOtherComprehensiveIncomeByItemLineItems to ifrs-full_OtherComprehensiveIncome" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable" xlink:label="ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable" xlink:title="ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:label="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:title="ifrs-full_CategoriesOfRelatedPartiesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable" xlink:to="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:title="Definition : ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable to ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:label="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:title="ifrs-full_EntitysTotalForRelatedPartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:to="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:title="Definition : ifrs-full_CategoriesOfRelatedPartiesAxis to ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:label="ifrs-full_EntitysTotalForRelatedPartiesMember_1" xlink:title="ifrs-full_EntitysTotalForRelatedPartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:to="ifrs-full_EntitysTotalForRelatedPartiesMember_1" xlink:title="Definition : ifrs-full_CategoriesOfRelatedPartiesAxis to ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProductsAndServicesAxis" xlink:label="ifrs-full_ProductsAndServicesAxis" xlink:title="ifrs-full_ProductsAndServicesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable" xlink:to="ifrs-full_ProductsAndServicesAxis" xlink:title="Definition : ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable to ifrs-full_ProductsAndServicesAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProductsAndServicesMember" xlink:label="ifrs-full_ProductsAndServicesMember" xlink:title="ifrs-full_ProductsAndServicesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ProductsAndServicesAxis" xlink:to="ifrs-full_ProductsAndServicesMember" xlink:title="Definition : ifrs-full_ProductsAndServicesAxis to ifrs-full_ProductsAndServicesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ConstructionRevenueMember" xlink:label="csan_ConstructionRevenueMember" xlink:title="csan_ConstructionRevenueMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_ConstructionRevenueMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_ConstructionRevenueMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GasDistributionMember" xlink:label="ifrs-full_GasDistributionMember" xlink:title="ifrs-full_GasDistributionMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="ifrs-full_GasDistributionMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to ifrs-full_GasDistributionMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LubricantsAndBasicOilMember" xlink:label="csan_LubricantsAndBasicOilMember" xlink:title="csan_LubricantsAndBasicOilMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_LubricantsAndBasicOilMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_LubricantsAndBasicOilMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OtherProductsMember" xlink:label="csan_OtherProductsMember" xlink:title="csan_OtherProductsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_OtherProductsMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_OtherProductsMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OtherServicesMember" xlink:label="csan_OtherServicesMember" xlink:title="csan_OtherServicesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_OtherServicesMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_OtherServicesMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PortElevationMember" xlink:label="csan_PortElevationMember" xlink:title="csan_PortElevationMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_PortElevationMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_PortElevationMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_TransportationMember" xlink:label="csan_TransportationMember" xlink:title="csan_TransportationMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_TransportationMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_TransportationMember" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ElectricityDistributionMember" xlink:label="ifrs-full_ElectricityDistributionMember" xlink:title="ifrs-full_ElectricityDistributionMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="ifrs-full_ElectricityDistributionMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to ifrs-full_ElectricityDistributionMember" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProductsAndServicesMember" xlink:label="ifrs-full_ProductsAndServicesMember_1" xlink:title="ifrs-full_ProductsAndServicesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ProductsAndServicesAxis" xlink:to="ifrs-full_ProductsAndServicesMember_1" xlink:title="Definition : ifrs-full_ProductsAndServicesAxis to ifrs-full_ProductsAndServicesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SegmentConsolidationItemsAxis" xlink:label="ifrs-full_SegmentConsolidationItemsAxis" xlink:title="ifrs-full_SegmentConsolidationItemsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable" xlink:to="ifrs-full_SegmentConsolidationItemsAxis" xlink:title="Definition : ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable to ifrs-full_SegmentConsolidationItemsAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:label="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:title="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SegmentConsolidationItemsAxis" xlink:to="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:title="Definition : ifrs-full_SegmentConsolidationItemsAxis to ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_EliminationMember" xlink:label="csan_EliminationMember" xlink:title="csan_EliminationMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:to="csan_EliminationMember" xlink:title="Definition : ifrs-full_EntitysTotalForSegmentConsolidationItemsMember to csan_EliminationMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:label="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember_1" xlink:title="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SegmentConsolidationItemsAxis" xlink:to="ifrs-full_EntitysTotalForSegmentConsolidationItemsMember_1" xlink:title="Definition : ifrs-full_SegmentConsolidationItemsAxis to ifrs-full_EntitysTotalForSegmentConsolidationItemsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SegmentsAxis" xlink:label="ifrs-full_SegmentsAxis" xlink:title="ifrs-full_SegmentsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable" xlink:to="ifrs-full_SegmentsAxis" xlink:title="Definition : ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable to ifrs-full_SegmentsAxis" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SegmentsMember" xlink:label="ifrs-full_SegmentsMember" xlink:title="ifrs-full_SegmentsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SegmentsAxis" xlink:to="ifrs-full_SegmentsMember" xlink:title="Definition : ifrs-full_SegmentsAxis to ifrs-full_SegmentsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SegmentsMember" xlink:label="ifrs-full_SegmentsMember_1" xlink:title="ifrs-full_SegmentsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SegmentsAxis" xlink:to="ifrs-full_SegmentsMember_1" xlink:title="Definition : ifrs-full_SegmentsAxis to ifrs-full_SegmentsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TimingOfTransferOfGoodsOrServicesAxis" xlink:label="ifrs-full_TimingOfTransferOfGoodsOrServicesAxis" xlink:title="ifrs-full_TimingOfTransferOfGoodsOrServicesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable" xlink:to="ifrs-full_TimingOfTransferOfGoodsOrServicesAxis" xlink:title="Definition : ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable to ifrs-full_TimingOfTransferOfGoodsOrServicesAxis" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TimingOfTransferOfGoodsOrServicesMember" xlink:label="ifrs-full_TimingOfTransferOfGoodsOrServicesMember" xlink:title="ifrs-full_TimingOfTransferOfGoodsOrServicesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_TimingOfTransferOfGoodsOrServicesAxis" xlink:to="ifrs-full_TimingOfTransferOfGoodsOrServicesMember" xlink:title="Definition : ifrs-full_TimingOfTransferOfGoodsOrServicesAxis to ifrs-full_TimingOfTransferOfGoodsOrServicesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GoodsOrServicesTransferredAtPointInTimeMember" xlink:label="ifrs-full_GoodsOrServicesTransferredAtPointInTimeMember" xlink:title="ifrs-full_GoodsOrServicesTransferredAtPointInTimeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_TimingOfTransferOfGoodsOrServicesMember" xlink:to="ifrs-full_GoodsOrServicesTransferredAtPointInTimeMember" xlink:title="Definition : ifrs-full_TimingOfTransferOfGoodsOrServicesMember to ifrs-full_GoodsOrServicesTransferredAtPointInTimeMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GoodsOrServicesTransferredOverTimeMember" xlink:label="ifrs-full_GoodsOrServicesTransferredOverTimeMember" xlink:title="ifrs-full_GoodsOrServicesTransferredOverTimeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_TimingOfTransferOfGoodsOrServicesMember" xlink:to="ifrs-full_GoodsOrServicesTransferredOverTimeMember" xlink:title="Definition : ifrs-full_TimingOfTransferOfGoodsOrServicesMember to ifrs-full_GoodsOrServicesTransferredOverTimeMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TimingOfTransferOfGoodsOrServicesMember" xlink:label="ifrs-full_TimingOfTransferOfGoodsOrServicesMember_1" xlink:title="ifrs-full_TimingOfTransferOfGoodsOrServicesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_TimingOfTransferOfGoodsOrServicesAxis" xlink:to="ifrs-full_TimingOfTransferOfGoodsOrServicesMember_1" xlink:title="Definition : ifrs-full_TimingOfTransferOfGoodsOrServicesAxis to ifrs-full_TimingOfTransferOfGoodsOrServicesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems" xlink:to="ifrs-full_RevenueFromContractsWithCustomers" xlink:title="Definition : ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersLineItems to ifrs-full_RevenueFromContractsWithCustomers" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/OtherincomeexpensesnetSummaryofDetailsofOtherincomeexpensesnetParentheticalDetail">
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OtherOperatingIncomeAndExpenseNetLineItems" xlink:label="csan_OtherOperatingIncomeAndExpenseNetLineItems" xlink:title="csan_OtherOperatingIncomeAndExpenseNetLineItems"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:to="ifrs-full_SharebasedPaymentArrangementsMember" xlink:title="Definition : ifrs-full_TypesOfSharebasedPaymentArrangementsAxis to ifrs-full_SharebasedPaymentArrangementsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DecemberTwelveTwoThousandTwelveMember" xlink:label="csan_DecemberTwelveTwoThousandTwelveMember" xlink:title="csan_DecemberTwelveTwoThousandTwelveMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SharebasedPaymentArrangementsMember" xlink:to="csan_DecemberTwelveTwoThousandTwelveMember" xlink:title="Definition : ifrs-full_SharebasedPaymentArrangementsMember to csan_DecemberTwelveTwoThousandTwelveMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AprilTwentyFourTwoThousandThirteenMember" xlink:label="csan_AprilTwentyFourTwoThousandThirteenMember" xlink:title="csan_AprilTwentyFourTwoThousandThirteenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SharebasedPaymentArrangementsMember" xlink:to="csan_AprilTwentyFourTwoThousandThirteenMember" xlink:title="Definition : ifrs-full_SharebasedPaymentArrangementsMember to csan_AprilTwentyFourTwoThousandThirteenMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AprilTwentyFiveTwoThousandFourteenMember" xlink:label="csan_AprilTwentyFiveTwoThousandFourteenMember" xlink:title="csan_AprilTwentyFiveTwoThousandFourteenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SharebasedPaymentArrangementsMember" xlink:to="csan_AprilTwentyFiveTwoThousandFourteenMember" xlink:title="Definition : ifrs-full_SharebasedPaymentArrangementsMember to csan_AprilTwentyFiveTwoThousandFourteenMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AugustThirtyOneTwoThousandFifteenMember" xlink:label="csan_AugustThirtyOneTwoThousandFifteenMember" xlink:title="csan_AugustThirtyOneTwoThousandFifteenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SharebasedPaymentArrangementsMember" xlink:to="csan_AugustThirtyOneTwoThousandFifteenMember" xlink:title="Definition : ifrs-full_SharebasedPaymentArrangementsMember to csan_AugustThirtyOneTwoThousandFifteenMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AugustEighteenTwoThousandElevenOneMember" xlink:label="csan_AugustEighteenTwoThousandElevenOneMember" xlink:title="csan_AugustEighteenTwoThousandElevenOneMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SharebasedPaymentArrangementsMember" xlink:to="csan_AugustEighteenTwoThousandElevenOneMember" xlink:title="Definition : ifrs-full_SharebasedPaymentArrangementsMember to csan_AugustEighteenTwoThousandElevenOneMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AugustEighteenTwoThousandElevenTwoMember" xlink:label="csan_AugustEighteenTwoThousandElevenTwoMember" xlink:title="csan_AugustEighteenTwoThousandElevenTwoMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SharebasedPaymentArrangementsMember" xlink:to="csan_AugustEighteenTwoThousandElevenTwoMember" xlink:title="Definition : ifrs-full_SharebasedPaymentArrangementsMember to csan_AugustEighteenTwoThousandElevenTwoMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_StockOptionProgramsMember" xlink:label="csan_StockOptionProgramsMember" xlink:title="csan_StockOptionProgramsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SharebasedPaymentArrangementsMember" xlink:to="csan_StockOptionProgramsMember" xlink:title="Definition : ifrs-full_SharebasedPaymentArrangementsMember to csan_StockOptionProgramsMember" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SharebasedPaymentArrangementsMember" xlink:label="ifrs-full_SharebasedPaymentArrangementsMember_1" xlink:title="ifrs-full_SharebasedPaymentArrangementsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:to="ifrs-full_SharebasedPaymentArrangementsMember_1" xlink:title="Definition : ifrs-full_TypesOfSharebasedPaymentArrangementsAxis to ifrs-full_SharebasedPaymentArrangementsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangeAxis" xlink:label="ifrs-full_RangeAxis" xlink:title="ifrs-full_RangeAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable" xlink:to="ifrs-full_RangeAxis" xlink:title="Definition : ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable to ifrs-full_RangeAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember" xlink:title="ifrs-full_RangesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_RangeAxis" xlink:to="ifrs-full_RangesMember" xlink:title="Definition : ifrs-full_RangeAxis to ifrs-full_RangesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BottomOfRangeMember" xlink:label="ifrs-full_BottomOfRangeMember" xlink:title="ifrs-full_BottomOfRangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RangesMember" xlink:to="ifrs-full_BottomOfRangeMember" xlink:title="Definition : ifrs-full_RangesMember to ifrs-full_BottomOfRangeMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TopOfRangeMember" xlink:label="ifrs-full_TopOfRangeMember" xlink:title="ifrs-full_TopOfRangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RangesMember" xlink:to="ifrs-full_TopOfRangeMember" xlink:title="Definition : ifrs-full_RangesMember to ifrs-full_TopOfRangeMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember_1" xlink:title="ifrs-full_RangesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_RangeAxis" xlink:to="ifrs-full_RangesMember_1" xlink:title="Definition : ifrs-full_RangeAxis to ifrs-full_RangesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ProgramNameAxis" xlink:label="csan_ProgramNameAxis" xlink:title="csan_ProgramNameAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable" xlink:to="csan_ProgramNameAxis" xlink:title="Definition : ifrs-full_DisclosureOfSignificantInvestmentsInSubsidiariesTable to csan_ProgramNameAxis" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ProgramNameDomain" xlink:label="csan_ProgramNameDomain" xlink:title="csan_ProgramNameDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="csan_ProgramNameAxis" xlink:to="csan_ProgramNameDomain" xlink:title="Definition : csan_ProgramNameAxis to csan_ProgramNameDomain" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ProgramNameDomain" xlink:label="csan_ProgramNameDomain_1" xlink:title="csan_ProgramNameDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="csan_ProgramNameAxis" xlink:to="csan_ProgramNameDomain_1" xlink:title="Definition : csan_ProgramNameAxis to csan_ProgramNameDomain" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DateOfGrantOfSharebasedPaymentArrangement" xlink:label="ifrs-full_DateOfGrantOfSharebasedPaymentArrangement" xlink:title="ifrs-full_DateOfGrantOfSharebasedPaymentArrangement"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfStockOptionActivityLineItems" xlink:to="ifrs-full_DateOfGrantOfSharebasedPaymentArrangement" xlink:title="Definition : csan_DisclosureOfStockOptionActivityLineItems to ifrs-full_DateOfGrantOfSharebasedPaymentArrangement" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NameOfSubsidiary" xlink:label="ifrs-full_NameOfSubsidiary" xlink:title="ifrs-full_NameOfSubsidiary"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfStockOptionActivityLineItems" xlink:to="ifrs-full_NameOfSubsidiary" xlink:title="Definition : csan_DisclosureOfStockOptionActivityLineItems to ifrs-full_NameOfSubsidiary" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ReplacementOfStockOptionPlan" xlink:label="csan_ReplacementOfStockOptionPlan" xlink:title="csan_ReplacementOfStockOptionPlan"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfStockOptionActivityLineItems" xlink:to="csan_ReplacementOfStockOptionPlan" xlink:title="Definition : csan_DisclosureOfStockOptionActivityLineItems to csan_ReplacementOfStockOptionPlan" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_WeightedAverageRemainingContractualLifeOfOutstandingShareOptions2019" xlink:label="ifrs-full_WeightedAverageRemainingContractualLifeOfOutstandingShareOptions2019" xlink:title="ifrs-full_WeightedAverageRemainingContractualLifeOfOutstandingShareOptions2019"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfStockOptionActivityLineItems" xlink:to="ifrs-full_WeightedAverageRemainingContractualLifeOfOutstandingShareOptions2019" xlink:title="Definition : csan_DisclosureOfStockOptionActivityLineItems to ifrs-full_WeightedAverageRemainingContractualLifeOfOutstandingShareOptions2019" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
</link:definitionLink>
<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/ShareBasedPaymentSummaryOfShareBasedPaymentArrangementsDetail">
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:label="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:title="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DateOfGrantOfSharebasedPaymentArrangement" xlink:label="ifrs-full_DateOfGrantOfSharebasedPaymentArrangement" xlink:title="ifrs-full_DateOfGrantOfSharebasedPaymentArrangement"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="ifrs-full_DateOfGrantOfSharebasedPaymentArrangement" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to ifrs-full_DateOfGrantOfSharebasedPaymentArrangement" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NameOfSubsidiary" xlink:label="ifrs-full_NameOfSubsidiary" xlink:title="ifrs-full_NameOfSubsidiary"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="ifrs-full_NameOfSubsidiary" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to ifrs-full_NameOfSubsidiary" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_WeightedAverageRemainingContractualLifeOfOutstandingShareOptions2019" xlink:label="ifrs-full_WeightedAverageRemainingContractualLifeOfOutstandingShareOptions2019" xlink:title="ifrs-full_WeightedAverageRemainingContractualLifeOfOutstandingShareOptions2019"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="ifrs-full_WeightedAverageRemainingContractualLifeOfOutstandingShareOptions2019" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to ifrs-full_WeightedAverageRemainingContractualLifeOfOutstandingShareOptions2019" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement" xlink:label="ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement" xlink:title="ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_NumberOfShareOptionsExercisedCanceledTransferred" xlink:label="csan_NumberOfShareOptionsExercisedCanceledTransferred" xlink:title="csan_NumberOfShareOptionsExercisedCanceledTransferred"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="csan_NumberOfShareOptionsExercisedCanceledTransferred" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to csan_NumberOfShareOptionsExercisedCanceledTransferred" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NumberOfOutstandingShareOptions" xlink:label="ifrs-full_NumberOfOutstandingShareOptions" xlink:title="ifrs-full_NumberOfOutstandingShareOptions"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="ifrs-full_NumberOfOutstandingShareOptions" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to ifrs-full_NumberOfOutstandingShareOptions" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:label="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:title="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:type="arc" use="optional" order="6" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangeAxis" xlink:label="ifrs-full_RangeAxis" xlink:title="ifrs-full_RangeAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:to="ifrs-full_RangeAxis" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable to ifrs-full_RangeAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember" xlink:title="ifrs-full_RangesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_RangeAxis" xlink:to="ifrs-full_RangesMember" xlink:title="Definition : ifrs-full_RangeAxis to ifrs-full_RangesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BottomOfRangeMember" xlink:label="ifrs-full_BottomOfRangeMember" xlink:title="ifrs-full_BottomOfRangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RangesMember" xlink:to="ifrs-full_BottomOfRangeMember" xlink:title="Definition : ifrs-full_RangesMember to ifrs-full_BottomOfRangeMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TopOfRangeMember" xlink:label="ifrs-full_TopOfRangeMember" xlink:title="ifrs-full_TopOfRangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RangesMember" xlink:to="ifrs-full_TopOfRangeMember" xlink:title="Definition : ifrs-full_RangesMember to ifrs-full_TopOfRangeMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember_1" xlink:title="ifrs-full_RangesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_RangeAxis" xlink:to="ifrs-full_RangesMember_1" xlink:title="Definition : ifrs-full_RangeAxis to ifrs-full_RangesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:label="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="ifrs-full_SignificantInvestmentsInSubsidiariesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:to="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable to ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanSAIndustriaeComercioMember" xlink:label="csan_CosanSAIndustriaeComercioMember" xlink:title="csan_CosanSAIndustriaeComercioMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanSAIndustriaeComercioMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanSAIndustriaeComercioMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ComgasMember" xlink:label="csan_ComgasMember" xlink:title="csan_ComgasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ComgasMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ComgasMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ComgasAndCompassGasEEnergiaSAMember" xlink:label="csan_ComgasAndCompassGasEEnergiaSAMember" xlink:title="csan_ComgasAndCompassGasEEnergiaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ComgasAndCompassGasEEnergiaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ComgasAndCompassGasEEnergiaSAMember" xlink:type="arc" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoSAMember" xlink:label="csan_RumoSAMember" xlink:title="csan_RumoSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoSAMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLimitedMember" xlink:label="csan_CosanLimitedMember" xlink:title="csan_CosanLimitedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanLimitedMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanLimitedMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_MooveMember" xlink:label="csan_MooveMember" xlink:title="csan_MooveMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_MooveMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_MooveMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLimitedAndMooveMember" xlink:label="csan_CosanLimitedAndMooveMember" xlink:title="csan_CosanLimitedAndMooveMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanLimitedAndMooveMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanLimitedAndMooveMember" xlink:type="arc" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLogisticaMember" xlink:label="csan_CosanLogisticaMember" xlink:title="csan_CosanLogisticaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanLogisticaMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanLogisticaMember" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CompassGasEEnergiaSAMember" xlink:label="csan_CompassGasEEnergiaSAMember" xlink:title="csan_CompassGasEEnergiaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CompassGasEEnergiaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CompassGasEEnergiaSAMember" xlink:type="arc" order="8" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AwardDatesAxis" xlink:label="csan_AwardDatesAxis" xlink:title="csan_AwardDatesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:to="csan_AwardDatesAxis" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable to csan_AwardDatesAxis" xlink:type="arc" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AwardDatesDomain" xlink:label="csan_AwardDatesDomain" xlink:title="csan_AwardDatesDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="csan_AwardDatesAxis" xlink:to="csan_AwardDatesDomain" xlink:title="Definition : csan_AwardDatesAxis to csan_AwardDatesDomain" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AprilTwentySevenTwoThousandSeventeenMember" xlink:label="csan_AprilTwentySevenTwoThousandSeventeenMember" xlink:title="csan_AprilTwentySevenTwoThousandSeventeenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_AprilTwentySevenTwoThousandSeventeenMember" xlink:title="Definition : csan_AwardDatesDomain to csan_AprilTwentySevenTwoThousandSeventeenMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_JulyThirtyOneTwoThousandSeventeenMember" xlink:label="csan_JulyThirtyOneTwoThousandSeventeenMember" xlink:title="csan_JulyThirtyOneTwoThousandSeventeenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_JulyThirtyOneTwoThousandSeventeenMember" xlink:title="Definition : csan_AwardDatesDomain to csan_JulyThirtyOneTwoThousandSeventeenMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_JulyThirtyOneTwoThousandEighteenMember" xlink:label="csan_JulyThirtyOneTwoThousandEighteenMember" xlink:title="csan_JulyThirtyOneTwoThousandEighteenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_JulyThirtyOneTwoThousandEighteenMember" xlink:title="Definition : csan_AwardDatesDomain to csan_JulyThirtyOneTwoThousandEighteenMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_JulyThirtyOneTwoThousandNineteenMember" xlink:label="csan_JulyThirtyOneTwoThousandNineteenMember" xlink:title="csan_JulyThirtyOneTwoThousandNineteenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_JulyThirtyOneTwoThousandNineteenMember" xlink:title="Definition : csan_AwardDatesDomain to csan_JulyThirtyOneTwoThousandNineteenMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_July31St2020Member" xlink:label="csan_July31St2020Member" xlink:title="csan_July31St2020Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_July31St2020Member" xlink:title="Definition : csan_AwardDatesDomain to csan_July31St2020Member" xlink:type="arc" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AprilTwentyTwoThousandSeventeenMember" xlink:label="csan_AprilTwentyTwoThousandSeventeenMember" xlink:title="csan_AprilTwentyTwoThousandSeventeenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_AprilTwentyTwoThousandSeventeenMember" xlink:title="Definition : csan_AwardDatesDomain to csan_AprilTwentyTwoThousandSeventeenMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AugustTwelveTwoThousandSeventeenMember" xlink:label="csan_AugustTwelveTwoThousandSeventeenMember" xlink:title="csan_AugustTwelveTwoThousandSeventeenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_AugustTwelveTwoThousandSeventeenMember" xlink:title="Definition : csan_AwardDatesDomain to csan_AugustTwelveTwoThousandSeventeenMember" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AugustOneTwoThousandEighteenMember" xlink:label="csan_AugustOneTwoThousandEighteenMember" xlink:title="csan_AugustOneTwoThousandEighteenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_AugustOneTwoThousandEighteenMember" xlink:title="Definition : csan_AwardDatesDomain to csan_AugustOneTwoThousandEighteenMember" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_February01St2020Member" xlink:label="csan_February01St2020Member" xlink:title="csan_February01St2020Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_February01St2020Member" xlink:title="Definition : csan_AwardDatesDomain to csan_February01St2020Member" xlink:type="arc" order="8" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OctoberOneTwoThousandFifteenOneMember" xlink:label="csan_OctoberOneTwoThousandFifteenOneMember" xlink:title="csan_OctoberOneTwoThousandFifteenOneMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_OctoberOneTwoThousandFifteenOneMember" xlink:title="Definition : csan_AwardDatesDomain to csan_OctoberOneTwoThousandFifteenOneMember" xlink:type="arc" use="optional" order="9" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_JanuaryTwoTwoThousandSeventeenMember" xlink:label="csan_JanuaryTwoTwoThousandSeventeenMember" xlink:title="csan_JanuaryTwoTwoThousandSeventeenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_JanuaryTwoTwoThousandSeventeenMember" xlink:title="Definition : csan_AwardDatesDomain to csan_JanuaryTwoTwoThousandSeventeenMember" xlink:type="arc" use="optional" order="10" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SeptemberOneTwoThousandSeventeenMember" xlink:label="csan_SeptemberOneTwoThousandSeventeenMember" xlink:title="csan_SeptemberOneTwoThousandSeventeenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_SeptemberOneTwoThousandSeventeenMember" xlink:title="Definition : csan_AwardDatesDomain to csan_SeptemberOneTwoThousandSeventeenMember" xlink:type="arc" use="optional" order="11" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AugustFifteenTwoThousandNineteenMember" xlink:label="csan_AugustFifteenTwoThousandNineteenMember" xlink:title="csan_AugustFifteenTwoThousandNineteenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_AugustFifteenTwoThousandNineteenMember" xlink:title="Definition : csan_AwardDatesDomain to csan_AugustFifteenTwoThousandNineteenMember" xlink:type="arc" use="optional" order="12" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_August15Th2019TwoMember" xlink:label="csan_August15Th2019TwoMember" xlink:title="csan_August15Th2019TwoMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_August15Th2019TwoMember" xlink:title="Definition : csan_AwardDatesDomain to csan_August15Th2019TwoMember" xlink:type="arc" order="13" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AugustEighteenTwoThousandElevenTwoMember" xlink:label="csan_AugustEighteenTwoThousandElevenTwoMember" xlink:title="csan_AugustEighteenTwoThousandElevenTwoMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_AugustEighteenTwoThousandElevenTwoMember" xlink:title="Definition : csan_AwardDatesDomain to csan_AugustEighteenTwoThousandElevenTwoMember" xlink:type="arc" use="optional" order="14" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DecemberTwelveTwoThousandTwelveMember" xlink:label="csan_DecemberTwelveTwoThousandTwelveMember" xlink:title="csan_DecemberTwelveTwoThousandTwelveMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_DecemberTwelveTwoThousandTwelveMember" xlink:title="Definition : csan_AwardDatesDomain to csan_DecemberTwelveTwoThousandTwelveMember" xlink:type="arc" use="optional" order="15" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AprilTwentyFourTwoThousandThirteenMember" xlink:label="csan_AprilTwentyFourTwoThousandThirteenMember" xlink:title="csan_AprilTwentyFourTwoThousandThirteenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_AprilTwentyFourTwoThousandThirteenMember" xlink:title="Definition : csan_AwardDatesDomain to csan_AprilTwentyFourTwoThousandThirteenMember" xlink:type="arc" use="optional" order="16" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AprilTwentyFiveTwoThousandFourteenMember" xlink:label="csan_AprilTwentyFiveTwoThousandFourteenMember" xlink:title="csan_AprilTwentyFiveTwoThousandFourteenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_AprilTwentyFiveTwoThousandFourteenMember" xlink:title="Definition : csan_AwardDatesDomain to csan_AprilTwentyFiveTwoThousandFourteenMember" xlink:type="arc" use="optional" order="17" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AugustThirtyOneTwoThousandFifteenMember" xlink:label="csan_AugustThirtyOneTwoThousandFifteenMember" xlink:title="csan_AugustThirtyOneTwoThousandFifteenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_AugustThirtyOneTwoThousandFifteenMember" xlink:title="Definition : csan_AwardDatesDomain to csan_AugustThirtyOneTwoThousandFifteenMember" xlink:type="arc" use="optional" order="18" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AugustEighteenTwoThousandSeventeenMember" xlink:label="csan_AugustEighteenTwoThousandSeventeenMember" xlink:title="csan_AugustEighteenTwoThousandSeventeenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_AugustEighteenTwoThousandSeventeenMember" xlink:title="Definition : csan_AwardDatesDomain to csan_AugustEighteenTwoThousandSeventeenMember" xlink:type="arc" use="optional" order="19" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SeptemberTwentyOneTwoThousandSeventeenMember" xlink:label="csan_SeptemberTwentyOneTwoThousandSeventeenMember" xlink:title="csan_SeptemberTwentyOneTwoThousandSeventeenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_SeptemberTwentyOneTwoThousandSeventeenMember" xlink:title="Definition : csan_AwardDatesDomain to csan_SeptemberTwentyOneTwoThousandSeventeenMember" xlink:type="arc" use="optional" order="20" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AugustEighteenTwoThousandSeventeenTwoMember" xlink:label="csan_AugustEighteenTwoThousandSeventeenTwoMember" xlink:title="csan_AugustEighteenTwoThousandSeventeenTwoMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_AwardDatesDomain" xlink:to="csan_AugustEighteenTwoThousandSeventeenTwoMember" xlink:title="Definition : csan_AwardDatesDomain to csan_AugustEighteenTwoThousandSeventeenTwoMember" xlink:type="arc" order="21" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AwardDatesDomain" xlink:label="csan_AwardDatesDomain_1" xlink:title="csan_AwardDatesDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="csan_AwardDatesAxis" xlink:to="csan_AwardDatesDomain_1" xlink:title="Definition : csan_AwardDatesAxis to csan_AwardDatesDomain" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:label="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:title="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:to="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable to ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SharebasedPaymentArrangementsMember" xlink:label="ifrs-full_SharebasedPaymentArrangementsMember" xlink:title="ifrs-full_SharebasedPaymentArrangementsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:to="ifrs-full_SharebasedPaymentArrangementsMember" xlink:title="Definition : ifrs-full_TypesOfSharebasedPaymentArrangementsAxis to ifrs-full_SharebasedPaymentArrangementsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_StockGrantProgramsMember" xlink:label="csan_StockGrantProgramsMember" xlink:title="csan_StockGrantProgramsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SharebasedPaymentArrangementsMember" xlink:to="csan_StockGrantProgramsMember" xlink:title="Definition : ifrs-full_SharebasedPaymentArrangementsMember to csan_StockGrantProgramsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_StockGrantModificationMember" xlink:label="csan_StockGrantModificationMember" xlink:title="csan_StockGrantModificationMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SharebasedPaymentArrangementsMember" xlink:to="csan_StockGrantModificationMember" xlink:title="Definition : ifrs-full_SharebasedPaymentArrangementsMember to csan_StockGrantModificationMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CashSettledTransactionsMember" xlink:label="csan_CashSettledTransactionsMember" xlink:title="csan_CashSettledTransactionsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SharebasedPaymentArrangementsMember" xlink:to="csan_CashSettledTransactionsMember" xlink:title="Definition : ifrs-full_SharebasedPaymentArrangementsMember to csan_CashSettledTransactionsMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SharebasedPaymentArrangementsMember" xlink:label="ifrs-full_SharebasedPaymentArrangementsMember_1" xlink:title="ifrs-full_SharebasedPaymentArrangementsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:to="ifrs-full_SharebasedPaymentArrangementsMember_1" xlink:title="Definition : ifrs-full_TypesOfSharebasedPaymentArrangementsAxis to ifrs-full_SharebasedPaymentArrangementsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ProgramNameAxis" xlink:label="csan_ProgramNameAxis" xlink:title="csan_ProgramNameAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:to="csan_ProgramNameAxis" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable to csan_ProgramNameAxis" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ProgramNameDomain" xlink:label="csan_ProgramNameDomain" xlink:title="csan_ProgramNameDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="csan_ProgramNameAxis" xlink:to="csan_ProgramNameDomain" xlink:title="Definition : csan_ProgramNameAxis to csan_ProgramNameDomain" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_ProgramNameDomain" xlink:to="csan_StockGrantModificationMember" xlink:title="Definition : csan_ProgramNameDomain to csan_StockGrantModificationMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ProgramNameDomain" xlink:label="csan_ProgramNameDomain_1" xlink:title="csan_ProgramNameDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="csan_ProgramNameAxis" xlink:to="csan_ProgramNameDomain_1" xlink:title="Definition : csan_ProgramNameAxis to csan_ProgramNameDomain" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/ShareBasedPaymentSummaryOfWeightedAverageFairValueOfProgramsGrantedAndPrincipalAssumptionsUsedInApplyingBlackScholesModelDetail">
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:label="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:title="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:type="arc" use="optional" order="0" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:label="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="ifrs-full_SignificantInvestmentsInSubsidiariesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:to="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable to ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ComgasMember" xlink:label="csan_ComgasMember" xlink:title="csan_ComgasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ComgasMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ComgasMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanSAIndustriaeComercioMember" xlink:label="csan_CosanSAIndustriaeComercioMember" xlink:title="csan_CosanSAIndustriaeComercioMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanSAIndustriaeComercioMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanSAIndustriaeComercioMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoSAMember" xlink:label="csan_RumoSAMember" xlink:title="csan_RumoSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoSAMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CompassGasEEnergiaMember" xlink:label="csan_CompassGasEEnergiaMember" xlink:title="csan_CompassGasEEnergiaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CompassGasEEnergiaMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CompassGasEEnergiaMember" xlink:type="arc" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:label="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:title="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:to="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable to ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SharebasedPaymentArrangementsMember" xlink:label="ifrs-full_SharebasedPaymentArrangementsMember" xlink:title="ifrs-full_SharebasedPaymentArrangementsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:to="ifrs-full_SharebasedPaymentArrangementsMember" xlink:title="Definition : ifrs-full_TypesOfSharebasedPaymentArrangementsAxis to ifrs-full_SharebasedPaymentArrangementsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_StockGrantProgramsMember" xlink:label="csan_StockGrantProgramsMember" xlink:title="csan_StockGrantProgramsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SharebasedPaymentArrangementsMember" xlink:to="csan_StockGrantProgramsMember" xlink:title="Definition : ifrs-full_SharebasedPaymentArrangementsMember to csan_StockGrantProgramsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SharebasedPaymentArrangementsMember" xlink:label="ifrs-full_SharebasedPaymentArrangementsMember_1" xlink:title="ifrs-full_SharebasedPaymentArrangementsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:to="ifrs-full_SharebasedPaymentArrangementsMember_1" xlink:title="Definition : ifrs-full_TypesOfSharebasedPaymentArrangementsAxis to ifrs-full_SharebasedPaymentArrangementsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DescriptionOfExpectedVolatilityShareOptionsGranted" xlink:label="ifrs-full_DescriptionOfExpectedVolatilityShareOptionsGranted" xlink:title="ifrs-full_DescriptionOfExpectedVolatilityShareOptionsGranted"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="ifrs-full_DescriptionOfExpectedVolatilityShareOptionsGranted" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to ifrs-full_DescriptionOfExpectedVolatilityShareOptionsGranted" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DescriptionOfRiskFreeInterestRateShareOptionsGranted" xlink:label="ifrs-full_DescriptionOfRiskFreeInterestRateShareOptionsGranted" xlink:title="ifrs-full_DescriptionOfRiskFreeInterestRateShareOptionsGranted"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="ifrs-full_DescriptionOfRiskFreeInterestRateShareOptionsGranted" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to ifrs-full_DescriptionOfRiskFreeInterestRateShareOptionsGranted" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ExpectedDividendAsPercentageShareOptionsGranted" xlink:label="ifrs-full_ExpectedDividendAsPercentageShareOptionsGranted" xlink:title="ifrs-full_ExpectedDividendAsPercentageShareOptionsGranted"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="ifrs-full_ExpectedDividendAsPercentageShareOptionsGranted" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to ifrs-full_ExpectedDividendAsPercentageShareOptionsGranted" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_WeightedAverageFairValueAtMeasurementDateShareOptionsGranted" xlink:label="ifrs-full_WeightedAverageFairValueAtMeasurementDateShareOptionsGranted" xlink:title="ifrs-full_WeightedAverageFairValueAtMeasurementDateShareOptionsGranted"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="ifrs-full_WeightedAverageFairValueAtMeasurementDateShareOptionsGranted" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to ifrs-full_WeightedAverageFairValueAtMeasurementDateShareOptionsGranted" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_WeightedAverageSharePriceShareOptionsGranted2019" xlink:label="ifrs-full_WeightedAverageSharePriceShareOptionsGranted2019" xlink:title="ifrs-full_WeightedAverageSharePriceShareOptionsGranted2019"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="ifrs-full_WeightedAverageSharePriceShareOptionsGranted2019" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to ifrs-full_WeightedAverageSharePriceShareOptionsGranted2019" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/ShareBasedPaymentSummaryOfNumberAndWeightedAverageExercisePricesOfShareOptionsDetail">
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:label="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:title="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:label="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:title="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:type="arc" use="optional" order="0" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:label="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:title="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable" xlink:to="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable to ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SharebasedPaymentArrangementsMember" xlink:label="ifrs-full_SharebasedPaymentArrangementsMember" xlink:title="ifrs-full_SharebasedPaymentArrangementsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:to="ifrs-full_SharebasedPaymentArrangementsMember" xlink:title="Definition : ifrs-full_TypesOfSharebasedPaymentArrangementsAxis to ifrs-full_SharebasedPaymentArrangementsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_StockGrantProgramsMember" xlink:label="csan_StockGrantProgramsMember" xlink:title="csan_StockGrantProgramsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SharebasedPaymentArrangementsMember" xlink:to="csan_StockGrantProgramsMember" xlink:title="Definition : ifrs-full_SharebasedPaymentArrangementsMember to csan_StockGrantProgramsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_StockOptionProgramsMember" xlink:label="csan_StockOptionProgramsMember" xlink:title="csan_StockOptionProgramsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SharebasedPaymentArrangementsMember" xlink:to="csan_StockOptionProgramsMember" xlink:title="Definition : ifrs-full_SharebasedPaymentArrangementsMember to csan_StockOptionProgramsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SharebasedPaymentArrangementsMember" xlink:label="ifrs-full_SharebasedPaymentArrangementsMember_1" xlink:title="ifrs-full_SharebasedPaymentArrangementsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_TypesOfSharebasedPaymentArrangementsAxis" xlink:to="ifrs-full_SharebasedPaymentArrangementsMember_1" xlink:title="Definition : ifrs-full_TypesOfSharebasedPaymentArrangementsAxis to ifrs-full_SharebasedPaymentArrangementsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NumberOfOutstandingShareOptions" xlink:label="ifrs-full_NumberOfOutstandingShareOptions" xlink:title="ifrs-full_NumberOfOutstandingShareOptions"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="ifrs-full_NumberOfOutstandingShareOptions" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to ifrs-full_NumberOfOutstandingShareOptions" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NumberOfShareOptionsForfeitedInSharebasedPaymentArrangement" xlink:label="ifrs-full_NumberOfShareOptionsForfeitedInSharebasedPaymentArrangement" xlink:title="ifrs-full_NumberOfShareOptionsForfeitedInSharebasedPaymentArrangement"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="ifrs-full_NumberOfShareOptionsForfeitedInSharebasedPaymentArrangement" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to ifrs-full_NumberOfShareOptionsForfeitedInSharebasedPaymentArrangement" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement" xlink:label="ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement" xlink:title="ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems" xlink:to="ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement" xlink:title="Definition : ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems to ifrs-full_NumberOfShareOptionsGrantedInSharebasedPaymentArrangement" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_NumberOfShareOptionsVestedInSharebasedPaymentArrangement" xlink:label="csan_NumberOfShareOptionsVestedInSharebasedPaymentArrangement" xlink:title="csan_NumberOfShareOptionsVestedInSharebasedPaymentArrangement"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_MajorBusinessCombinationMember" xlink:label="ifrs-full_MajorBusinessCombinationMember" xlink:title="ifrs-full_MajorBusinessCombinationMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_NonadjustingEventsMember" xlink:to="ifrs-full_MajorBusinessCombinationMember" xlink:title="Definition : ifrs-full_NonadjustingEventsMember to ifrs-full_MajorBusinessCombinationMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ProposalOfDividendsMember" xlink:label="csan_ProposalOfDividendsMember" xlink:title="csan_ProposalOfDividendsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_NonadjustingEventsMember" xlink:to="csan_ProposalOfDividendsMember" xlink:title="Definition : ifrs-full_NonadjustingEventsMember to csan_ProposalOfDividendsMember" xlink:type="arc" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_OrdinaryGeneralMeetingMember" xlink:label="csan_OrdinaryGeneralMeetingMember" xlink:title="csan_OrdinaryGeneralMeetingMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_NonadjustingEventsMember" xlink:to="csan_OrdinaryGeneralMeetingMember" xlink:title="Definition : ifrs-full_NonadjustingEventsMember to csan_OrdinaryGeneralMeetingMember" xlink:type="arc" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NonadjustingEventsMember" xlink:label="ifrs-full_NonadjustingEventsMember_1" xlink:title="ifrs-full_NonadjustingEventsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_NonadjustingEventsAfterReportingPeriodAxis" xlink:to="ifrs-full_NonadjustingEventsMember_1" xlink:title="Definition : ifrs-full_NonadjustingEventsAfterReportingPeriodAxis to ifrs-full_NonadjustingEventsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BorrowingsByNameAxis" xlink:label="ifrs-full_BorrowingsByNameAxis" xlink:title="ifrs-full_BorrowingsByNameAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodTable" xlink:to="ifrs-full_BorrowingsByNameAxis" xlink:title="Definition : ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodTable to ifrs-full_BorrowingsByNameAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BorrowingsByNameMember" xlink:label="ifrs-full_BorrowingsByNameMember" xlink:title="ifrs-full_BorrowingsByNameMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_BorrowingsByNameAxis" xlink:to="ifrs-full_BorrowingsByNameMember" xlink:title="Definition : ifrs-full_BorrowingsByNameAxis to ifrs-full_BorrowingsByNameMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PromissoryNotesMember" xlink:label="csan_PromissoryNotesMember" xlink:title="csan_PromissoryNotesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_PromissoryNotesMember" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_PromissoryNotesMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DebenturesMember" xlink:label="csan_DebenturesMember" xlink:title="csan_DebenturesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_BorrowingsByNameMember" xlink:to="csan_DebenturesMember" xlink:title="Definition : ifrs-full_BorrowingsByNameMember to csan_DebenturesMember" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BorrowingsByNameMember" xlink:label="ifrs-full_BorrowingsByNameMember_1" xlink:title="ifrs-full_BorrowingsByNameMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_BorrowingsByNameAxis" xlink:to="ifrs-full_BorrowingsByNameMember_1" xlink:title="Definition : ifrs-full_BorrowingsByNameAxis to ifrs-full_BorrowingsByNameMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BorrowingsByTypeAxis" xlink:label="csan_BorrowingsByTypeAxis" xlink:title="csan_BorrowingsByTypeAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodTable" xlink:to="csan_BorrowingsByTypeAxis" xlink:title="Definition : ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodTable to csan_BorrowingsByTypeAxis" xlink:type="arc" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BorrowingsByTypeMember" xlink:label="csan_BorrowingsByTypeMember" xlink:title="csan_BorrowingsByTypeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="csan_BorrowingsByTypeAxis" xlink:to="csan_BorrowingsByTypeMember" xlink:title="Definition : csan_BorrowingsByTypeAxis to csan_BorrowingsByTypeMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_UnsecuredNonConvertibleMember" xlink:label="csan_UnsecuredNonConvertibleMember" xlink:title="csan_UnsecuredNonConvertibleMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_BorrowingsByTypeMember" xlink:to="csan_UnsecuredNonConvertibleMember" xlink:title="Definition : csan_BorrowingsByTypeMember to csan_UnsecuredNonConvertibleMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BorrowingsByTypeMember" xlink:label="csan_BorrowingsByTypeMember_1" xlink:title="csan_BorrowingsByTypeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="csan_BorrowingsByTypeAxis" xlink:to="csan_BorrowingsByTypeMember_1" xlink:title="Definition : csan_BorrowingsByTypeAxis to csan_BorrowingsByTypeMember" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:label="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="ifrs-full_SignificantInvestmentsInSubsidiariesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodTable" xlink:to="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="Definition : ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodTable to ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ComgasMember" xlink:label="csan_ComgasMember" xlink:title="csan_ComgasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ComgasMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ComgasMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoSAMember" xlink:label="csan_RumoSAMember" xlink:title="csan_RumoSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoSAMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CompassGasEEnergiaSAMember" xlink:label="csan_CompassGasEEnergiaSAMember" xlink:title="csan_CompassGasEEnergiaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CompassGasEEnergiaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CompassGasEEnergiaSAMember" xlink:type="arc" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_JointVenturesAxis" xlink:label="ifrs-full_JointVenturesAxis" xlink:title="ifrs-full_JointVenturesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodTable" xlink:to="ifrs-full_JointVenturesAxis" xlink:title="Definition : ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodTable to ifrs-full_JointVenturesAxis" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForJointVenturesMember" xlink:label="ifrs-full_EntitysTotalForJointVenturesMember" xlink:title="ifrs-full_EntitysTotalForJointVenturesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_JointVenturesAxis" xlink:to="ifrs-full_EntitysTotalForJointVenturesMember" xlink:title="Definition : ifrs-full_JointVenturesAxis to ifrs-full_EntitysTotalForJointVenturesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RaizenGroupMember" xlink:label="csan_RaizenGroupMember" xlink:title="csan_RaizenGroupMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForJointVenturesMember" xlink:to="csan_RaizenGroupMember" xlink:title="Definition : ifrs-full_EntitysTotalForJointVenturesMember to csan_RaizenGroupMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForJointVenturesMember" xlink:label="ifrs-full_EntitysTotalForJointVenturesMember_1" xlink:title="ifrs-full_EntitysTotalForJointVenturesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_JointVenturesAxis" xlink:to="ifrs-full_EntitysTotalForJointVenturesMember_1" xlink:title="Definition : ifrs-full_JointVenturesAxis to ifrs-full_EntitysTotalForJointVenturesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfShareCapitalAxis" xlink:label="ifrs-full_ClassesOfShareCapitalAxis" xlink:title="ifrs-full_ClassesOfShareCapitalAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodTable" xlink:to="ifrs-full_ClassesOfShareCapitalAxis" xlink:title="Definition : ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodTable to ifrs-full_ClassesOfShareCapitalAxis" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfShareCapitalMember" xlink:label="ifrs-full_ClassesOfShareCapitalMember" xlink:title="ifrs-full_ClassesOfShareCapitalMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfShareCapitalAxis" xlink:to="ifrs-full_ClassesOfShareCapitalMember" xlink:title="Definition : ifrs-full_ClassesOfShareCapitalAxis to ifrs-full_ClassesOfShareCapitalMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_OrdinarySharesMember" xlink:label="ifrs-full_OrdinarySharesMember" xlink:title="ifrs-full_OrdinarySharesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfShareCapitalMember" xlink:to="ifrs-full_OrdinarySharesMember" xlink:title="Definition : ifrs-full_ClassesOfShareCapitalMember to ifrs-full_OrdinarySharesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PreferenceSharesMember" xlink:label="ifrs-full_PreferenceSharesMember" xlink:title="ifrs-full_PreferenceSharesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfShareCapitalMember" xlink:to="ifrs-full_PreferenceSharesMember" xlink:title="Definition : ifrs-full_ClassesOfShareCapitalMember to ifrs-full_PreferenceSharesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RedeemableSharesMember" xlink:label="csan_RedeemableSharesMember" xlink:title="csan_RedeemableSharesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfShareCapitalMember" xlink:to="csan_RedeemableSharesMember" xlink:title="Definition : ifrs-full_ClassesOfShareCapitalMember to csan_RedeemableSharesMember" xlink:type="arc" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfShareCapitalMember" xlink:label="ifrs-full_ClassesOfShareCapitalMember_1" xlink:title="ifrs-full_ClassesOfShareCapitalMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfShareCapitalAxis" xlink:to="ifrs-full_ClassesOfShareCapitalMember_1" xlink:title="Definition : ifrs-full_ClassesOfShareCapitalAxis to ifrs-full_ClassesOfShareCapitalMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BusinessCombinationsAxis" xlink:label="ifrs-full_BusinessCombinationsAxis" xlink:title="ifrs-full_BusinessCombinationsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodTable" xlink:to="ifrs-full_BusinessCombinationsAxis" xlink:title="Definition : ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodTable to ifrs-full_BusinessCombinationsAxis" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:label="ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:title="ifrs-full_EntitysTotalForBusinessCombinationsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_BusinessCombinationsAxis" xlink:to="ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:title="Definition : ifrs-full_BusinessCombinationsAxis to ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BiosevSAMember" xlink:label="csan_BiosevSAMember" xlink:title="csan_BiosevSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:to="csan_BiosevSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForBusinessCombinationsMember to csan_BiosevSAMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:label="ifrs-full_EntitysTotalForBusinessCombinationsMember_1" xlink:title="ifrs-full_EntitysTotalForBusinessCombinationsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_BusinessCombinationsAxis" xlink:to="ifrs-full_EntitysTotalForBusinessCombinationsMember_1" xlink:title="Definition : ifrs-full_BusinessCombinationsAxis to ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangeAxis" xlink:label="ifrs-full_RangeAxis" xlink:title="ifrs-full_RangeAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodTable" xlink:to="ifrs-full_RangeAxis" xlink:title="Definition : ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodTable to ifrs-full_RangeAxis" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember" xlink:title="ifrs-full_RangesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_RangeAxis" xlink:to="ifrs-full_RangesMember" xlink:title="Definition : ifrs-full_RangeAxis to ifrs-full_RangesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TopOfRangeMember" xlink:label="ifrs-full_TopOfRangeMember" xlink:title="ifrs-full_TopOfRangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RangesMember" xlink:to="ifrs-full_TopOfRangeMember" xlink:title="Definition : ifrs-full_RangesMember to ifrs-full_TopOfRangeMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember_1" xlink:title="ifrs-full_RangesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_RangeAxis" xlink:to="ifrs-full_RangesMember_1" xlink:title="Definition : ifrs-full_RangeAxis to ifrs-full_RangesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:title="dei_LegalEntityAxis"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" xlink:title="Definition : dei_LegalEntityAxis to dei_EntityDomain" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="csan_CosanSAMember" xlink:title="Definition : dei_EntityDomain to csan_CosanSAMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain_1" xlink:title="dei_EntityDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain_1" xlink:title="Definition : dei_LegalEntityAxis to dei_EntityDomain" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_StockSplitConversionRatio" xlink:label="csan_StockSplitConversionRatio" xlink:title="csan_StockSplitConversionRatio"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodLineItems" xlink:to="csan_StockSplitConversionRatio" xlink:title="Definition : ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodLineItems to csan_StockSplitConversionRatio" xlink:type="arc" order="9" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_NumberOfSharesAvailableForStockSplit" xlink:label="csan_NumberOfSharesAvailableForStockSplit" xlink:title="csan_NumberOfSharesAvailableForStockSplit"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodLineItems" xlink:to="csan_NumberOfSharesAvailableForStockSplit" xlink:title="Definition : ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodLineItems to csan_NumberOfSharesAvailableForStockSplit" xlink:type="arc" order="10" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_NumberOfSharesOutstandingAfterStockSplit" xlink:label="csan_NumberOfSharesOutstandingAfterStockSplit" xlink:title="csan_NumberOfSharesOutstandingAfterStockSplit"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodLineItems" xlink:to="csan_NumberOfSharesOutstandingAfterStockSplit" xlink:title="Definition : ifrs-full_DisclosureOfNonadjustingEventsAfterReportingPeriodLineItems to csan_NumberOfSharesOutstandingAfterStockSplit" xlink:type="arc" order="11" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_JointVenturesAxis" xlink:label="ifrs-full_JointVenturesAxis" xlink:title="ifrs-full_JointVenturesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsTable" xlink:to="ifrs-full_JointVenturesAxis" xlink:title="Definition : ifrs-full_DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsTable to ifrs-full_JointVenturesAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForJointVenturesMember" xlink:label="ifrs-full_EntitysTotalForJointVenturesMember" xlink:title="ifrs-full_EntitysTotalForJointVenturesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_JointVenturesAxis" xlink:to="ifrs-full_EntitysTotalForJointVenturesMember" xlink:title="Definition : ifrs-full_JointVenturesAxis to ifrs-full_EntitysTotalForJointVenturesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanSAMember" xlink:label="csan_CosanSAMember" xlink:title="csan_CosanSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForJointVenturesMember" xlink:to="csan_CosanSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForJointVenturesMember to csan_CosanSAMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForJointVenturesMember" xlink:label="ifrs-full_EntitysTotalForJointVenturesMember_1" xlink:title="ifrs-full_EntitysTotalForJointVenturesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_JointVenturesAxis" xlink:to="ifrs-full_EntitysTotalForJointVenturesMember_1" xlink:title="Definition : ifrs-full_JointVenturesAxis to ifrs-full_EntitysTotalForJointVenturesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangeAxis" xlink:label="ifrs-full_RangeAxis" xlink:title="ifrs-full_RangeAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsTable" xlink:to="ifrs-full_RangeAxis" xlink:title="Definition : ifrs-full_DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsTable to ifrs-full_RangeAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember" xlink:title="ifrs-full_RangesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_RangeAxis" xlink:to="ifrs-full_RangesMember" xlink:title="Definition : ifrs-full_RangeAxis to ifrs-full_RangesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember_1" xlink:title="ifrs-full_RangesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_RangeAxis" xlink:to="ifrs-full_RangesMember_1" xlink:title="Definition : ifrs-full_RangeAxis to ifrs-full_RangesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsTable" xlink:to="dei_LegalEntityAxis" xlink:title="Definition : ifrs-full_DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsTable to dei_LegalEntityAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:title="dei_EntityDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" xlink:title="Definition : dei_LegalEntityAxis to dei_EntityDomain" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLogisticaSAMember" xlink:label="csan_CosanLogisticaSAMember" xlink:title="csan_CosanLogisticaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="csan_CosanLogisticaSAMember" xlink:title="Definition : dei_EntityDomain to csan_CosanLogisticaSAMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain_1" xlink:title="dei_EntityDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain_1" xlink:title="Definition : dei_LegalEntityAxis to dei_EntityDomain" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfAssetsAxis" xlink:label="ifrs-full_ClassesOfAssetsAxis" xlink:title="ifrs-full_ClassesOfAssetsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsTable" xlink:to="ifrs-full_ClassesOfAssetsAxis" xlink:title="Definition : ifrs-full_DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsTable to ifrs-full_ClassesOfAssetsAxis" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfAssetsMember" xlink:label="ifrs-full_ClassesOfAssetsMember" xlink:title="ifrs-full_ClassesOfAssetsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfAssetsAxis" xlink:to="ifrs-full_ClassesOfAssetsMember" xlink:title="Definition : ifrs-full_ClassesOfAssetsAxis to ifrs-full_ClassesOfAssetsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RailroadNetworkMember" xlink:label="csan_RailroadNetworkMember" xlink:title="csan_RailroadNetworkMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfAssetsMember" xlink:to="csan_RailroadNetworkMember" xlink:title="Definition : ifrs-full_ClassesOfAssetsMember to csan_RailroadNetworkMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfAssetsMember" xlink:label="ifrs-full_ClassesOfAssetsMember_1" xlink:title="ifrs-full_ClassesOfAssetsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfAssetsAxis" xlink:to="ifrs-full_ClassesOfAssetsMember_1" xlink:title="Definition : ifrs-full_ClassesOfAssetsAxis to ifrs-full_ClassesOfAssetsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfIntangibleAssetsAndGoodwillAxis" xlink:label="ifrs-full_ClassesOfIntangibleAssetsAndGoodwillAxis" xlink:title="ifrs-full_ClassesOfIntangibleAssetsAndGoodwillAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsTable" xlink:to="ifrs-full_ClassesOfIntangibleAssetsAndGoodwillAxis" xlink:title="Definition : ifrs-full_DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsTable to ifrs-full_ClassesOfIntangibleAssetsAndGoodwillAxis" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_IntangibleAssetsAndGoodwillMember" xlink:label="ifrs-full_IntangibleAssetsAndGoodwillMember" xlink:title="ifrs-full_IntangibleAssetsAndGoodwillMember"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_IntangibleAssetsOtherThanGoodwillMember" xlink:label="ifrs-full_IntangibleAssetsOtherThanGoodwillMember" xlink:title="ifrs-full_IntangibleAssetsOtherThanGoodwillMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_IntangibleAssetsAndGoodwillMember" xlink:to="ifrs-full_IntangibleAssetsOtherThanGoodwillMember" xlink:title="Definition : ifrs-full_IntangibleAssetsAndGoodwillMember to ifrs-full_IntangibleAssetsOtherThanGoodwillMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_IntangibleAssetsAndGoodwillMember" xlink:label="ifrs-full_IntangibleAssetsAndGoodwillMember_1" xlink:title="ifrs-full_IntangibleAssetsAndGoodwillMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfIntangibleAssetsAndGoodwillAxis" xlink:to="ifrs-full_IntangibleAssetsAndGoodwillMember_1" xlink:title="Definition : ifrs-full_ClassesOfIntangibleAssetsAndGoodwillAxis to ifrs-full_IntangibleAssetsAndGoodwillMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PercentageOfCashPaymentInAuction" xlink:label="csan_PercentageOfCashPaymentInAuction" xlink:title="csan_PercentageOfCashPaymentInAuction"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsLineItems" xlink:to="csan_PaymentsForAuction" xlink:title="Definition : ifrs-full_DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretationsLineItems to csan_PaymentsForAuction" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:label="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:title="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LeasesRelatedToConcessionPayable" xlink:label="csan_LeasesRelatedToConcessionPayable" xlink:title="csan_LeasesRelatedToConcessionPayable"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LeasesAndGrantsRelatedToConcessionPayable" xlink:label="csan_LeasesAndGrantsRelatedToConcessionPayable" xlink:title="csan_LeasesAndGrantsRelatedToConcessionPayable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:to="csan_LeasesAndGrantsRelatedToConcessionPayable" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems to csan_LeasesAndGrantsRelatedToConcessionPayable" xlink:type="arc" order="2" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_NumberOfInstallmentsForConcessionAgreement" xlink:label="csan_NumberOfInstallmentsForConcessionAgreement" xlink:title="csan_NumberOfInstallmentsForConcessionAgreement"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:to="csan_NumberOfInstallmentsForConcessionAgreement" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems to csan_NumberOfInstallmentsForConcessionAgreement" xlink:type="arc" order="5" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems" xlink:to="csan_InstallmentsAmountFallingDueOfGrantsConcessionPayable" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsLineItems to csan_InstallmentsAmountFallingDueOfGrantsConcessionPayable" xlink:type="arc" order="6" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfLiabilitiesAxis" xlink:label="ifrs-full_ClassesOfLiabilitiesAxis" xlink:title="ifrs-full_ClassesOfLiabilitiesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable" xlink:to="ifrs-full_ClassesOfLiabilitiesAxis" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable to ifrs-full_ClassesOfLiabilitiesAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_LiabilitiesMember" xlink:label="ifrs-full_LiabilitiesMember" xlink:title="ifrs-full_LiabilitiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfLiabilitiesAxis" xlink:to="ifrs-full_LiabilitiesMember" xlink:title="Definition : ifrs-full_ClassesOfLiabilitiesAxis to ifrs-full_LiabilitiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_LeaseLiabilitiesMember" xlink:label="ifrs-full_LeaseLiabilitiesMember" xlink:title="ifrs-full_LeaseLiabilitiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_LiabilitiesMember" xlink:to="ifrs-full_LeaseLiabilitiesMember" xlink:title="Definition : ifrs-full_LiabilitiesMember to ifrs-full_LeaseLiabilitiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_GrantsPayableMember" xlink:label="csan_GrantsPayableMember" xlink:title="csan_GrantsPayableMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_LiabilitiesMember" xlink:to="csan_GrantsPayableMember" xlink:title="Definition : ifrs-full_LiabilitiesMember to csan_GrantsPayableMember" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_LiabilitiesMember" xlink:label="ifrs-full_LiabilitiesMember_1" xlink:title="ifrs-full_LiabilitiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfLiabilitiesAxis" xlink:to="ifrs-full_LiabilitiesMember_1" xlink:title="Definition : ifrs-full_ClassesOfLiabilitiesAxis to ifrs-full_LiabilitiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:label="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="ifrs-full_SignificantInvestmentsInSubsidiariesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable" xlink:to="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="Definition : csan_DisclosureOfConcessionsPayableAndJudicialDepositsTable to ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoMalhaSulSAMember" xlink:label="csan_RumoMalhaSulSAMember" xlink:title="csan_RumoMalhaSulSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoMalhaSulSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoMalhaSulSAMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoMalhaPaulistaSAMember" xlink:label="csan_RumoMalhaPaulistaSAMember" xlink:title="csan_RumoMalhaPaulistaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoMalhaPaulistaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoMalhaPaulistaSAMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoMalhaOesteSAMember" xlink:label="csan_RumoMalhaOesteSAMember" xlink:title="csan_RumoMalhaOesteSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoMalhaOesteSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoMalhaOesteSAMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ElevacoesPortuariasSAMember" xlink:label="csan_ElevacoesPortuariasSAMember" xlink:title="csan_ElevacoesPortuariasSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ElevacoesPortuariasSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ElevacoesPortuariasSAMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PortoferLtdaMember" xlink:label="csan_PortoferLtdaMember" xlink:title="csan_PortoferLtdaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_PortoferLtdaMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_PortoferLtdaMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoMalhaCentralSAMember" xlink:label="csan_RumoMalhaCentralSAMember" xlink:title="csan_RumoMalhaCentralSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoMalhaCentralSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoMalhaCentralSAMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/CommitmentsDetail">
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfDetailedInformationAboutCommitmentsTable" xlink:label="csan_DisclosureOfDetailedInformationAboutCommitmentsTable" xlink:title="csan_DisclosureOfDetailedInformationAboutCommitmentsTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="csan_DisclosureOfDetailedInformationAboutCommitmentsLineItems" xlink:to="csan_DisclosureOfDetailedInformationAboutCommitmentsTable" xlink:title="Definition : csan_DisclosureOfDetailedInformationAboutCommitmentsLineItems to csan_DisclosureOfDetailedInformationAboutCommitmentsTable" xlink:type="arc" order="0" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:label="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="ifrs-full_SignificantInvestmentsInSubsidiariesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfDetailedInformationAboutCommitmentsTable" xlink:to="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="Definition : csan_DisclosureOfDetailedInformationAboutCommitmentsTable to ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ComgasMember" xlink:label="csan_ComgasMember" xlink:title="csan_ComgasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ComgasMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ComgasMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoSAMember" xlink:label="csan_RumoSAMember" xlink:title="csan_RumoSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoSAMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoMalhaPaulistaSAMember" xlink:label="csan_RumoMalhaPaulistaSAMember" xlink:title="csan_RumoMalhaPaulistaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoMalhaPaulistaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoMalhaPaulistaSAMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoMalhaCentralSAMember" xlink:label="csan_RumoMalhaCentralSAMember" xlink:title="csan_RumoMalhaCentralSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoMalhaCentralSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoMalhaCentralSAMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfDetailedInformationAboutCommitmentsTable" xlink:to="ifrs-full_ProductsAndServicesAxis" xlink:title="Definition : csan_DisclosureOfDetailedInformationAboutCommitmentsTable to ifrs-full_ProductsAndServicesAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProductsAndServicesMember" xlink:label="ifrs-full_ProductsAndServicesMember" xlink:title="ifrs-full_ProductsAndServicesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ProductsAndServicesAxis" xlink:to="ifrs-full_ProductsAndServicesMember" xlink:title="Definition : ifrs-full_ProductsAndServicesAxis to ifrs-full_ProductsAndServicesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GasDistributionMember" xlink:label="ifrs-full_GasDistributionMember" xlink:title="ifrs-full_GasDistributionMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="ifrs-full_GasDistributionMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to ifrs-full_GasDistributionMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PortElevationMember" xlink:label="csan_PortElevationMember" xlink:title="csan_PortElevationMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_PortElevationMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_PortElevationMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangeAxis" xlink:label="ifrs-full_RangeAxis" xlink:title="ifrs-full_RangeAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfDetailedInformationAboutCommitmentsTable" xlink:to="ifrs-full_RangeAxis" xlink:title="Definition : csan_DisclosureOfDetailedInformationAboutCommitmentsTable to ifrs-full_RangeAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember" xlink:title="ifrs-full_RangesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_RangeAxis" xlink:to="ifrs-full_RangesMember" xlink:title="Definition : ifrs-full_RangeAxis to ifrs-full_RangesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BottomOfRangeMember" xlink:label="ifrs-full_BottomOfRangeMember" xlink:title="ifrs-full_BottomOfRangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RangesMember" xlink:to="ifrs-full_BottomOfRangeMember" xlink:title="Definition : ifrs-full_RangesMember to ifrs-full_BottomOfRangeMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_TopOfRangeMember" xlink:label="ifrs-full_TopOfRangeMember" xlink:title="ifrs-full_TopOfRangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RangesMember" xlink:to="ifrs-full_TopOfRangeMember" xlink:title="Definition : ifrs-full_RangesMember to ifrs-full_TopOfRangeMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_FinancialCommitmentInEstimatedPresentValue" xlink:label="csan_FinancialCommitmentInEstimatedPresentValue" xlink:title="csan_FinancialCommitmentInEstimatedPresentValue"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfDetailedInformationAboutCommitmentsLineItems" xlink:to="csan_FinancialCommitmentInEstimatedPresentValue" xlink:title="Definition : csan_DisclosureOfDetailedInformationAboutCommitmentsLineItems to csan_FinancialCommitmentInEstimatedPresentValue" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_EstimatedInvestmentsToBeMadeForSubConcessionContracts" xlink:label="csan_EstimatedInvestmentsToBeMadeForSubConcessionContracts" xlink:title="csan_EstimatedInvestmentsToBeMadeForSubConcessionContracts"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfDetailedInformationAboutCommitmentsLineItems" xlink:to="csan_EstimatedInvestmentsToBeMadeForSubConcessionContracts" xlink:title="Definition : csan_DisclosureOfDetailedInformationAboutCommitmentsLineItems to csan_EstimatedInvestmentsToBeMadeForSubConcessionContracts" xlink:type="arc" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ObligationsOfEstimatedInvestmentsForSubConcessionContracts" xlink:label="csan_ObligationsOfEstimatedInvestmentsForSubConcessionContracts" xlink:title="csan_ObligationsOfEstimatedInvestmentsForSubConcessionContracts"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="csan_StatementOfFinancialStatementsTable" xlink:title="Definition : srt_CondensedFinancialStatementsCaptionsLineItems to csan_StatementOfFinancialStatementsTable" xlink:type="arc" use="optional" order="2" xbrldt:closed="true" xbrldt:contextElement="segment"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_StatementOfFinancialStatementsTable" xlink:to="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:title="Definition : csan_StatementOfFinancialStatementsTable to ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:label="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:title="ifrs-full_EntitysTotalForRelatedPartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:to="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:title="Definition : ifrs-full_CategoriesOfRelatedPartiesAxis to ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CompanhiaDeGasDeSaoPauloMember" xlink:label="csan_CompanhiaDeGasDeSaoPauloMember" xlink:title="csan_CompanhiaDeGasDeSaoPauloMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_CompanhiaDeGasDeSaoPauloMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_CompanhiaDeGasDeSaoPauloMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_CosanLogisticaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_CosanLogisticaSAMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_CosanSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_CosanSAMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_RumoSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_RumoSAMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CompassGasEEnergiaSAMember" xlink:label="csan_CompassGasEEnergiaSAMember" xlink:title="csan_CompassGasEEnergiaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_CompassGasEEnergiaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_CompassGasEEnergiaSAMember" xlink:type="arc" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ComgasMember" xlink:label="csan_ComgasMember" xlink:title="csan_ComgasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_ComgasMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_ComgasMember" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SinlogTecnologiaEmLogisticaSaMember" xlink:label="csan_SinlogTecnologiaEmLogisticaSaMember" xlink:title="csan_SinlogTecnologiaEmLogisticaSaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:to="csan_SinlogTecnologiaEmLogisticaSaMember" xlink:title="Definition : ifrs-full_EntitysTotalForRelatedPartiesMember to csan_SinlogTecnologiaEmLogisticaSaMember" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:label="ifrs-full_EntitysTotalForRelatedPartiesMember_1" xlink:title="ifrs-full_EntitysTotalForRelatedPartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_CategoriesOfRelatedPartiesAxis" xlink:to="ifrs-full_EntitysTotalForRelatedPartiesMember_1" xlink:title="Definition : ifrs-full_CategoriesOfRelatedPartiesAxis to ifrs-full_EntitysTotalForRelatedPartiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_GuaranteeFeeRate" xlink:label="csan_GuaranteeFeeRate" xlink:title="csan_GuaranteeFeeRate"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems" xlink:to="csan_GuaranteeFeeRate" xlink:title="Definition : ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems to csan_GuaranteeFeeRate" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_BalanceOfBankGuaranteesContracted" xlink:label="csan_BalanceOfBankGuaranteesContracted" xlink:title="csan_BalanceOfBankGuaranteesContracted"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems" xlink:to="csan_BalanceOfBankGuaranteesContracted" xlink:title="Definition : ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems to csan_BalanceOfBankGuaranteesContracted" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BorrowingsInterestRate" xlink:label="ifrs-full_BorrowingsInterestRate" xlink:title="ifrs-full_BorrowingsInterestRate"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems" xlink:to="ifrs-full_BorrowingsInterestRate" xlink:title="Definition : ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems to ifrs-full_BorrowingsInterestRate" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable" xlink:label="ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable" xlink:title="ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems" xlink:to="ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable" xlink:title="Definition : ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems to ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable" xlink:type="arc" use="optional" order="3" xbrldt:closed="true" xbrldt:contextElement="segment"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_FinancialLiabilitiesTypeMember" xlink:label="ifrs-full_FinancialLiabilitiesTypeMember" xlink:title="ifrs-full_FinancialLiabilitiesTypeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_TypesOfFinancialLiabilitiesAxis" xlink:to="ifrs-full_FinancialLiabilitiesTypeMember" xlink:title="Definition : ifrs-full_TypesOfFinancialLiabilitiesAxis to ifrs-full_FinancialLiabilitiesTypeMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SecuredBorrowingsMember" xlink:label="csan_SecuredBorrowingsMember" xlink:title="csan_SecuredBorrowingsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_FinancialLiabilitiesTypeMember" xlink:to="csan_SecuredBorrowingsMember" xlink:title="Definition : ifrs-full_FinancialLiabilitiesTypeMember to csan_SecuredBorrowingsMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_FinancialLiabilitiesTypeMember" xlink:label="ifrs-full_FinancialLiabilitiesTypeMember_1" xlink:title="ifrs-full_FinancialLiabilitiesTypeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_TypesOfFinancialLiabilitiesAxis" xlink:to="ifrs-full_FinancialLiabilitiesTypeMember_1" xlink:title="Definition : ifrs-full_TypesOfFinancialLiabilitiesAxis to ifrs-full_FinancialLiabilitiesTypeMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BorrowingsByNameAxis" xlink:label="ifrs-full_BorrowingsByNameAxis" xlink:title="ifrs-full_BorrowingsByNameAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable" xlink:to="ifrs-full_BorrowingsByNameAxis" xlink:title="Definition : ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable to ifrs-full_BorrowingsByNameAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BorrowingsByNameMember" xlink:label="ifrs-full_BorrowingsByNameMember" xlink:title="ifrs-full_BorrowingsByNameMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_BorrowingsByNameAxis" xlink:to="ifrs-full_BorrowingsByNameMember" xlink:title="Definition : ifrs-full_BorrowingsByNameAxis to ifrs-full_BorrowingsByNameMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_EuropeanInvestmentBankMember" xlink:label="csan_EuropeanInvestmentBankMember" xlink:title="csan_EuropeanInvestmentBankMember"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BorrowingsByNameMember" xlink:label="ifrs-full_BorrowingsByNameMember_1" xlink:title="ifrs-full_BorrowingsByNameMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_BorrowingsByNameAxis" xlink:to="ifrs-full_BorrowingsByNameMember_1" xlink:title="Definition : ifrs-full_BorrowingsByNameAxis to ifrs-full_BorrowingsByNameMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable" xlink:to="ifrs-full_TypesOfInterestRatesAxis" xlink:title="Definition : ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsTable to ifrs-full_TypesOfInterestRatesAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_InterestRateTypesMember" xlink:label="ifrs-full_InterestRateTypesMember" xlink:title="ifrs-full_InterestRateTypesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_TypesOfInterestRatesAxis" xlink:to="ifrs-full_InterestRateTypesMember" xlink:title="Definition : ifrs-full_TypesOfInterestRatesAxis to ifrs-full_InterestRateTypesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CDIIndexMember" xlink:label="csan_CDIIndexMember" xlink:title="csan_CDIIndexMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_CDIIndexMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_CDIIndexMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_TJLPIndexMember" xlink:label="csan_TJLPIndexMember" xlink:title="csan_TJLPIndexMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_InterestRateTypesMember" xlink:to="csan_TJLPIndexMember" xlink:title="Definition : ifrs-full_InterestRateTypesMember to csan_TJLPIndexMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember" xlink:title="ifrs-full_RangesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_RangeAxis" xlink:to="ifrs-full_RangesMember" xlink:title="Definition : ifrs-full_RangeAxis to ifrs-full_RangesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_WeightedAverageMember" xlink:label="ifrs-full_WeightedAverageMember" xlink:title="ifrs-full_WeightedAverageMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_RangesMember" xlink:to="ifrs-full_WeightedAverageMember" xlink:title="Definition : ifrs-full_RangesMember to ifrs-full_WeightedAverageMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_RangesMember" xlink:label="ifrs-full_RangesMember_1" xlink:title="ifrs-full_RangesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_RangeAxis" xlink:to="ifrs-full_RangesMember_1" xlink:title="Definition : ifrs-full_RangeAxis to ifrs-full_RangesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionLink xlink:type="extended" xlink:role="http://www.cosan.com/role/FinancialAssetsAndLiabilitiesSummaryOfForeignCurrencyRelatedHedgingInstrumentsAndInterestRateSwapsDetail">
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<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:title="dei_EntityDomain"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanSAMember" xlink:label="csan_CosanSAMember" xlink:title="csan_CosanSAMember"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_IssueOfEquity" xlink:label="ifrs-full_IssueOfEquity" xlink:title="ifrs-full_IssueOfEquity"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfDevelopmentOfCompanyLineItems" xlink:to="ifrs-full_IssueOfEquity" xlink:title="Definition : csan_DisclosureOfDevelopmentOfCompanyLineItems to ifrs-full_IssueOfEquity" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PercentageOfIssuanceOfNewCommonSharesForInvestmentAgreement" xlink:label="csan_PercentageOfIssuanceOfNewCommonSharesForInvestmentAgreement" xlink:title="csan_PercentageOfIssuanceOfNewCommonSharesForInvestmentAgreement"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ContractualTerm" xlink:label="csan_ContractualTerm" xlink:title="csan_ContractualTerm"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ContractualBidAmount" xlink:label="csan_ContractualBidAmount" xlink:title="csan_ContractualBidAmount"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PercentageOfCashPaymentInAuction" xlink:label="csan_PercentageOfCashPaymentInAuction" xlink:title="csan_PercentageOfCashPaymentInAuction"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_VolumeTransportedPerKilometer" xlink:label="csan_VolumeTransportedPerKilometer" xlink:title="csan_VolumeTransportedPerKilometer"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PercentageOfDecreasedDemandForNaturalGas" xlink:label="csan_PercentageOfDecreasedDemandForNaturalGas" xlink:title="csan_PercentageOfDecreasedDemandForNaturalGas"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_PercentageOfIncreasedVolumeSold" xlink:label="csan_PercentageOfIncreasedVolumeSold" xlink:title="csan_PercentageOfIncreasedVolumeSold"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProfitLoss" xlink:label="ifrs-full_ProfitLoss" xlink:title="ifrs-full_ProfitLoss"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CashAndCashEquivalentsAndMarketableSecurities" xlink:label="csan_CashAndCashEquivalentsAndMarketableSecurities" xlink:title="csan_CashAndCashEquivalentsAndMarketableSecurities"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfDevelopmentOfCompanyLineItems" xlink:to="csan_CashAndCashEquivalentsAndMarketableSecurities" xlink:title="Definition : csan_DisclosureOfDevelopmentOfCompanyLineItems to csan_CashAndCashEquivalentsAndMarketableSecurities" xlink:type="arc" order="35" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProceedsFromSalesOrMaturityOfFinancialInstrumentsClassifiedAsInvestingActivities" xlink:label="ifrs-full_ProceedsFromSalesOrMaturityOfFinancialInstrumentsClassifiedAsInvestingActivities" xlink:title="ifrs-full_ProceedsFromSalesOrMaturityOfFinancialInstrumentsClassifiedAsInvestingActivities"/>
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<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ProceedsFromFinancingFacilitiesContractedByJointVentures" xlink:label="csan_ProceedsFromFinancingFacilitiesContractedByJointVentures" xlink:title="csan_ProceedsFromFinancingFacilitiesContractedByJointVentures"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfDevelopmentOfCompanyLineItems" xlink:to="csan_ProceedsFromFinancingFacilitiesContractedByJointVentures" xlink:title="Definition : csan_DisclosureOfDevelopmentOfCompanyLineItems to csan_ProceedsFromFinancingFacilitiesContractedByJointVentures" xlink:type="arc" order="37" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_LeverageRatio" xlink:label="csan_LeverageRatio" xlink:title="csan_LeverageRatio"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfDevelopmentOfCompanyLineItems" xlink:to="csan_LeverageRatio" xlink:title="Definition : csan_DisclosureOfDevelopmentOfCompanyLineItems to csan_LeverageRatio" xlink:type="arc" order="38" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_DisclosureOfBackgroundAndOperationsTable" xlink:label="csan_DisclosureOfBackgroundAndOperationsTable" xlink:title="csan_DisclosureOfBackgroundAndOperationsTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="csan_DisclosureOfDevelopmentOfCompanyLineItems" xlink:to="csan_DisclosureOfBackgroundAndOperationsTable" xlink:title="Definition : csan_DisclosureOfDevelopmentOfCompanyLineItems to csan_DisclosureOfBackgroundAndOperationsTable" xlink:type="arc" use="optional" order="39" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:title="dei_LegalEntityAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfBackgroundAndOperationsTable" xlink:to="dei_LegalEntityAxis" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsTable to dei_LegalEntityAxis" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:title="dei_EntityDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" xlink:title="Definition : dei_LegalEntityAxis to dei_EntityDomain" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanSAMember" xlink:label="csan_CosanSAMember" xlink:title="csan_CosanSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="csan_CosanSAMember" xlink:title="Definition : dei_EntityDomain to csan_CosanSAMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain_1" xlink:title="dei_EntityDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain_1" xlink:title="Definition : dei_LegalEntityAxis to dei_EntityDomain" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:label="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="ifrs-full_SignificantInvestmentsInSubsidiariesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfBackgroundAndOperationsTable" xlink:to="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsTable to ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RaizenCombustiveisSAMember" xlink:label="csan_RaizenCombustiveisSAMember" xlink:title="csan_RaizenCombustiveisSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RaizenCombustiveisSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RaizenCombustiveisSAMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CosanLubesInvestmentsLimitedMember" xlink:label="csan_CosanLubesInvestmentsLimitedMember" xlink:title="csan_CosanLubesInvestmentsLimitedMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_CosanLubesInvestmentsLimitedMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_CosanLubesInvestmentsLimitedMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoSAMember" xlink:label="csan_RumoSAMember" xlink:title="csan_RumoSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoSAMember" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ComgasMember" xlink:label="csan_ComgasMember" xlink:title="csan_ComgasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_ComgasMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_ComgasMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RumoMalhaPaulistaSAMember" xlink:label="csan_RumoMalhaPaulistaSAMember" xlink:title="csan_RumoMalhaPaulistaSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForSubsidiariesMember" xlink:to="csan_RumoMalhaPaulistaSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForSubsidiariesMember to csan_RumoMalhaPaulistaSAMember" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForSubsidiariesMember" xlink:label="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="ifrs-full_EntitysTotalForSubsidiariesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SignificantInvestmentsInSubsidiariesAxis" xlink:to="ifrs-full_EntitysTotalForSubsidiariesMember_1" xlink:title="Definition : ifrs-full_SignificantInvestmentsInSubsidiariesAxis to ifrs-full_EntitysTotalForSubsidiariesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_BusinessCombinationsAxis" xlink:label="ifrs-full_BusinessCombinationsAxis" xlink:title="ifrs-full_BusinessCombinationsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfBackgroundAndOperationsTable" xlink:to="ifrs-full_BusinessCombinationsAxis" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsTable to ifrs-full_BusinessCombinationsAxis" xlink:type="arc" use="optional" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:label="ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:title="ifrs-full_EntitysTotalForBusinessCombinationsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_BusinessCombinationsAxis" xlink:to="ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:title="Definition : ifrs-full_BusinessCombinationsAxis to ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RaizenArgentinaMember" xlink:label="csan_RaizenArgentinaMember" xlink:title="csan_RaizenArgentinaMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:to="csan_RaizenArgentinaMember" xlink:title="Definition : ifrs-full_EntitysTotalForBusinessCombinationsMember to csan_RaizenArgentinaMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:label="ifrs-full_EntitysTotalForBusinessCombinationsMember_1" xlink:title="ifrs-full_EntitysTotalForBusinessCombinationsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_BusinessCombinationsAxis" xlink:to="ifrs-full_EntitysTotalForBusinessCombinationsMember_1" xlink:title="Definition : ifrs-full_BusinessCombinationsAxis to ifrs-full_EntitysTotalForBusinessCombinationsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NonadjustingEventsAfterReportingPeriodAxis" xlink:label="ifrs-full_NonadjustingEventsAfterReportingPeriodAxis" xlink:title="ifrs-full_NonadjustingEventsAfterReportingPeriodAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfBackgroundAndOperationsTable" xlink:to="ifrs-full_NonadjustingEventsAfterReportingPeriodAxis" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsTable to ifrs-full_NonadjustingEventsAfterReportingPeriodAxis" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NonadjustingEventsMember" xlink:label="ifrs-full_NonadjustingEventsMember" xlink:title="ifrs-full_NonadjustingEventsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_NonadjustingEventsAfterReportingPeriodAxis" xlink:to="ifrs-full_NonadjustingEventsMember" xlink:title="Definition : ifrs-full_NonadjustingEventsAfterReportingPeriodAxis to ifrs-full_NonadjustingEventsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_MajorOrdinaryShareTransactionsMember" xlink:label="ifrs-full_MajorOrdinaryShareTransactionsMember" xlink:title="ifrs-full_MajorOrdinaryShareTransactionsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_NonadjustingEventsMember" xlink:to="ifrs-full_MajorOrdinaryShareTransactionsMember" xlink:title="Definition : ifrs-full_NonadjustingEventsMember to ifrs-full_MajorOrdinaryShareTransactionsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_NonadjustingEventsMember" xlink:label="ifrs-full_NonadjustingEventsMember_1" xlink:title="ifrs-full_NonadjustingEventsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_NonadjustingEventsAfterReportingPeriodAxis" xlink:to="ifrs-full_NonadjustingEventsMember_1" xlink:title="Definition : ifrs-full_NonadjustingEventsAfterReportingPeriodAxis to ifrs-full_NonadjustingEventsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfAssetsAxis" xlink:label="ifrs-full_ClassesOfAssetsAxis" xlink:title="ifrs-full_ClassesOfAssetsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfBackgroundAndOperationsTable" xlink:to="ifrs-full_ClassesOfAssetsAxis" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsTable to ifrs-full_ClassesOfAssetsAxis" xlink:type="arc" use="optional" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfAssetsMember" xlink:label="ifrs-full_ClassesOfAssetsMember" xlink:title="ifrs-full_ClassesOfAssetsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfAssetsAxis" xlink:to="ifrs-full_ClassesOfAssetsMember" xlink:title="Definition : ifrs-full_ClassesOfAssetsAxis to ifrs-full_ClassesOfAssetsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfAssetsMember" xlink:to="csan_RailroadNetworkMember" xlink:title="Definition : ifrs-full_ClassesOfAssetsMember to csan_RailroadNetworkMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfAssetsMember" xlink:label="ifrs-full_ClassesOfAssetsMember_1" xlink:title="ifrs-full_ClassesOfAssetsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfAssetsAxis" xlink:to="ifrs-full_ClassesOfAssetsMember_1" xlink:title="Definition : ifrs-full_ClassesOfAssetsAxis to ifrs-full_ClassesOfAssetsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_JointVenturesAxis" xlink:label="ifrs-full_JointVenturesAxis" xlink:title="ifrs-full_JointVenturesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfBackgroundAndOperationsTable" xlink:to="ifrs-full_JointVenturesAxis" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsTable to ifrs-full_JointVenturesAxis" xlink:type="arc" use="optional" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForJointVenturesMember" xlink:label="ifrs-full_EntitysTotalForJointVenturesMember" xlink:title="ifrs-full_EntitysTotalForJointVenturesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_JointVenturesAxis" xlink:to="ifrs-full_EntitysTotalForJointVenturesMember" xlink:title="Definition : ifrs-full_JointVenturesAxis to ifrs-full_EntitysTotalForJointVenturesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_RedeIntegradaDeLojasDeConvenenciasEProximidadeSAMember" xlink:label="csan_RedeIntegradaDeLojasDeConvenenciasEProximidadeSAMember" xlink:title="csan_RedeIntegradaDeLojasDeConvenenciasEProximidadeSAMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_EntitysTotalForJointVenturesMember" xlink:to="csan_RedeIntegradaDeLojasDeConvenenciasEProximidadeSAMember" xlink:title="Definition : ifrs-full_EntitysTotalForJointVenturesMember to csan_RedeIntegradaDeLojasDeConvenenciasEProximidadeSAMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_EntitysTotalForJointVenturesMember" xlink:label="ifrs-full_EntitysTotalForJointVenturesMember_1" xlink:title="ifrs-full_EntitysTotalForJointVenturesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_JointVenturesAxis" xlink:to="ifrs-full_EntitysTotalForJointVenturesMember_1" xlink:title="Definition : ifrs-full_JointVenturesAxis to ifrs-full_EntitysTotalForJointVenturesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfBackgroundAndOperationsTable" xlink:to="ifrs-full_ClassesOfShareCapitalAxis" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsTable to ifrs-full_ClassesOfShareCapitalAxis" xlink:type="arc" use="optional" order="6" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfShareCapitalAxis" xlink:to="ifrs-full_ClassesOfShareCapitalMember" xlink:title="Definition : ifrs-full_ClassesOfShareCapitalAxis to ifrs-full_ClassesOfShareCapitalMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_PreferenceSharesMember" xlink:label="ifrs-full_PreferenceSharesMember" xlink:title="ifrs-full_PreferenceSharesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ClassesOfShareCapitalMember" xlink:to="ifrs-full_PreferenceSharesMember" xlink:title="Definition : ifrs-full_ClassesOfShareCapitalMember to ifrs-full_PreferenceSharesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfShareCapitalMember" xlink:label="ifrs-full_ClassesOfShareCapitalMember_1" xlink:title="ifrs-full_ClassesOfShareCapitalMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfShareCapitalAxis" xlink:to="ifrs-full_ClassesOfShareCapitalMember_1" xlink:title="Definition : ifrs-full_ClassesOfShareCapitalAxis to ifrs-full_ClassesOfShareCapitalMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CounterpartiesAxis" xlink:label="ifrs-full_CounterpartiesAxis" xlink:title="ifrs-full_CounterpartiesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfBackgroundAndOperationsTable" xlink:to="ifrs-full_CounterpartiesAxis" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsTable to ifrs-full_CounterpartiesAxis" xlink:type="arc" use="optional" order="7" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CounterpartiesMember" xlink:label="ifrs-full_CounterpartiesMember" xlink:title="ifrs-full_CounterpartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_CounterpartiesAxis" xlink:to="ifrs-full_CounterpartiesMember" xlink:title="Definition : ifrs-full_CounterpartiesAxis to ifrs-full_CounterpartiesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_CounterpartiesMember" xlink:to="csan_BancoSantanderBrasilSAMember" xlink:title="Definition : ifrs-full_CounterpartiesMember to csan_BancoSantanderBrasilSAMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_CounterpartiesMember" xlink:label="ifrs-full_CounterpartiesMember_1" xlink:title="ifrs-full_CounterpartiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_CounterpartiesAxis" xlink:to="ifrs-full_CounterpartiesMember_1" xlink:title="Definition : ifrs-full_CounterpartiesAxis to ifrs-full_CounterpartiesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ClassesOfFinancialAssetsAxis" xlink:label="ifrs-full_ClassesOfFinancialAssetsAxis" xlink:title="ifrs-full_ClassesOfFinancialAssetsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfBackgroundAndOperationsTable" xlink:to="ifrs-full_ClassesOfFinancialAssetsAxis" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsTable to ifrs-full_ClassesOfFinancialAssetsAxis" xlink:type="arc" use="optional" order="8" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_FinancialAssetsMember" xlink:label="ifrs-full_FinancialAssetsMember" xlink:title="ifrs-full_FinancialAssetsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ClassesOfFinancialAssetsAxis" xlink:to="ifrs-full_FinancialAssetsMember" xlink:title="Definition : ifrs-full_ClassesOfFinancialAssetsAxis to ifrs-full_FinancialAssetsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_SwapContractForSharesMember" xlink:label="csan_SwapContractForSharesMember" xlink:title="csan_SwapContractForSharesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_FinancialAssetsMember" xlink:to="csan_SwapContractForSharesMember" xlink:title="Definition : ifrs-full_FinancialAssetsMember to csan_SwapContractForSharesMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_FinancialAssetsMember" xlink:label="ifrs-full_FinancialAssetsMember_1" xlink:title="ifrs-full_FinancialAssetsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ClassesOfFinancialAssetsAxis" xlink:to="ifrs-full_FinancialAssetsMember_1" xlink:title="Definition : ifrs-full_ClassesOfFinancialAssetsAxis to ifrs-full_FinancialAssetsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_UnusualOrInfrequentItemsAxis" xlink:label="csan_UnusualOrInfrequentItemsAxis" xlink:title="csan_UnusualOrInfrequentItemsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfBackgroundAndOperationsTable" xlink:to="csan_UnusualOrInfrequentItemsAxis" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsTable to csan_UnusualOrInfrequentItemsAxis" xlink:type="arc" order="9" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_UnusualOrInfrequentItemsDomain" xlink:label="csan_UnusualOrInfrequentItemsDomain" xlink:title="csan_UnusualOrInfrequentItemsDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="csan_UnusualOrInfrequentItemsAxis" xlink:to="csan_UnusualOrInfrequentItemsDomain" xlink:title="Definition : csan_UnusualOrInfrequentItemsAxis to csan_UnusualOrInfrequentItemsDomain" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CovidNineteenMember" xlink:label="csan_CovidNineteenMember" xlink:title="csan_CovidNineteenMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_UnusualOrInfrequentItemsDomain" xlink:to="csan_CovidNineteenMember" xlink:title="Definition : csan_UnusualOrInfrequentItemsDomain to csan_CovidNineteenMember" xlink:type="arc" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_UnusualOrInfrequentItemsDomain" xlink:label="csan_UnusualOrInfrequentItemsDomain_1" xlink:title="csan_UnusualOrInfrequentItemsDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="csan_UnusualOrInfrequentItemsAxis" xlink:to="csan_UnusualOrInfrequentItemsDomain_1" xlink:title="Definition : csan_UnusualOrInfrequentItemsAxis to csan_UnusualOrInfrequentItemsDomain" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SegmentsAxis" xlink:label="ifrs-full_SegmentsAxis" xlink:title="ifrs-full_SegmentsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfBackgroundAndOperationsTable" xlink:to="ifrs-full_SegmentsAxis" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsTable to ifrs-full_SegmentsAxis" xlink:type="arc" use="optional" order="10" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SegmentsMember" xlink:label="ifrs-full_SegmentsMember" xlink:title="ifrs-full_SegmentsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_SegmentsAxis" xlink:to="ifrs-full_SegmentsMember" xlink:title="Definition : ifrs-full_SegmentsAxis to ifrs-full_SegmentsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_RaizenCombustiveisMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_RaizenCombustiveisMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_LogisticsMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_LogisticsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_GasAndEnergyMember" xlink:label="csan_GasAndEnergyMember" xlink:title="csan_GasAndEnergyMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_GasAndEnergyMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_GasAndEnergyMember" xlink:type="arc" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_MooveMember" xlink:label="csan_MooveMember" xlink:title="csan_MooveMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_SegmentsMember" xlink:to="csan_MooveMember" xlink:title="Definition : ifrs-full_SegmentsMember to csan_MooveMember" xlink:type="arc" use="optional" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_SegmentsMember" xlink:label="ifrs-full_SegmentsMember_1" xlink:title="ifrs-full_SegmentsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_SegmentsAxis" xlink:to="ifrs-full_SegmentsMember_1" xlink:title="Definition : ifrs-full_SegmentsAxis to ifrs-full_SegmentsMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProductsAndServicesAxis" xlink:label="ifrs-full_ProductsAndServicesAxis" xlink:title="ifrs-full_ProductsAndServicesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfBackgroundAndOperationsTable" xlink:to="ifrs-full_ProductsAndServicesAxis" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsTable to ifrs-full_ProductsAndServicesAxis" xlink:type="arc" use="optional" order="11" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProductsAndServicesMember" xlink:label="ifrs-full_ProductsAndServicesMember" xlink:title="ifrs-full_ProductsAndServicesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_ProductsAndServicesAxis" xlink:to="ifrs-full_ProductsAndServicesMember" xlink:title="Definition : ifrs-full_ProductsAndServicesAxis to ifrs-full_ProductsAndServicesMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_FuelsMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_FuelsMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_GasolineAndEthanolMember" xlink:label="csan_GasolineAndEthanolMember" xlink:title="csan_GasolineAndEthanolMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_GasolineAndEthanolMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_GasolineAndEthanolMember" xlink:type="arc" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_AviationFuelsMember" xlink:label="csan_AviationFuelsMember" xlink:title="csan_AviationFuelsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_AviationFuelsMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_AviationFuelsMember" xlink:type="arc" order="2" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_IndustrialSegmentMember" xlink:label="csan_IndustrialSegmentMember" xlink:title="csan_IndustrialSegmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_IndustrialSegmentMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_IndustrialSegmentMember" xlink:type="arc" order="3" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_CommercialSegmentMember" xlink:label="csan_CommercialSegmentMember" xlink:title="csan_CommercialSegmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_CommercialSegmentMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_CommercialSegmentMember" xlink:type="arc" order="4" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="csan-20201231.xsd#csan_ResidentialSegmentMember" xlink:label="csan_ResidentialSegmentMember" xlink:title="csan_ResidentialSegmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_ProductsAndServicesMember" xlink:to="csan_ResidentialSegmentMember" xlink:title="Definition : ifrs-full_ProductsAndServicesMember to csan_ResidentialSegmentMember" xlink:type="arc" order="5" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_ProductsAndServicesMember" xlink:label="ifrs-full_ProductsAndServicesMember_1" xlink:title="ifrs-full_ProductsAndServicesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_ProductsAndServicesAxis" xlink:to="ifrs-full_ProductsAndServicesMember_1" xlink:title="Definition : ifrs-full_ProductsAndServicesAxis to ifrs-full_ProductsAndServicesMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="csan_DisclosureOfBackgroundAndOperationsTable" xlink:to="ifrs-full_GeographicalAreasAxis" xlink:title="Definition : csan_DisclosureOfBackgroundAndOperationsTable to ifrs-full_GeographicalAreasAxis" xlink:type="arc" use="optional" order="12" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GeographicalAreasMember" xlink:label="ifrs-full_GeographicalAreasMember" xlink:title="ifrs-full_GeographicalAreasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="ifrs-full_GeographicalAreasAxis" xlink:to="ifrs-full_GeographicalAreasMember" xlink:title="Definition : ifrs-full_GeographicalAreasAxis to ifrs-full_GeographicalAreasMember" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_GeographicalAreasMember" xlink:to="country_BR" xlink:title="Definition : ifrs-full_GeographicalAreasMember to country_BR" xlink:type="arc" use="optional" order="0" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_AR" xlink:label="country_AR" xlink:title="country_AR"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ifrs-full_GeographicalAreasMember" xlink:to="country_AR" xlink:title="Definition : ifrs-full_GeographicalAreasMember to country_AR" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
<link:loc xlink:type="locator" xlink:href="http://xbrl.ifrs.org/taxonomy/2019-03-27/full_ifrs/full_ifrs-cor_2019-03-27.xsd#ifrs-full_GeographicalAreasMember" xlink:label="ifrs-full_GeographicalAreasMember_1" xlink:title="ifrs-full_GeographicalAreasMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ifrs-full_GeographicalAreasAxis" xlink:to="ifrs-full_GeographicalAreasMember_1" xlink:title="Definition : ifrs-full_GeographicalAreasAxis to ifrs-full_GeographicalAreasMember" xlink:type="arc" use="optional" order="1" xbrldt:closed="false"/>
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<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="csan_DisclosureOfDevelopmentOfCompanyLineItems" xlink:to="ifrs-full_CurrentAssetsLiabilities" xlink:title="Definition : csan_DisclosureOfDevelopmentOfCompanyLineItems to ifrs-full_CurrentAssetsLiabilities" xlink:type="arc" use="optional" order="41" xbrldt:closed="false"/>
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7 Subsequent Filings that Reference this Filing

  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

 6/30/23  Cosan S.A.                        20-F/A     12/31/22   17:7.3M                                   IRIS Business Svcs/FA
 4/24/23  Cosan S.A.                        20-F       12/31/22  224:74M                                    IRIS Business Svcs/FA
 9/28/22  Cosan S.A.                        20-F/A     12/31/21   17:6.2M                                   IRIS Business Svcs/FA
 6/14/22  Queluz Holdings Ltd.              SC 13D                 2:136K Cosan S.A.                        Davis Polk & … LLP 01/FA
 5/16/22  Cosan S.A.                        20-F       12/31/21  208:57M                                    IRIS Business Svcs/FA
12/17/21  Cosan S.A.                        20-F/A     12/31/20   17:5M                                     IRIS Business Svcs/FA
 9/03/21  Cosan S.A.                        20-F/A     12/31/20   17:5.9M                                   IRIS Business Svcs/FA


9 Previous Filings that this Filing References

  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

 2/24/21  JPMorgan Chase Bank N… Depositary F-6                    3:327K Cosan S.A.                        E-Data Systems, Inc./FA
 5/28/20  Cosan Ltd.                        20-F       12/31/19  194:44M                                    Donnelley … Solutions/FA
 4/27/18  Cosan Ltd.                        20-F       12/31/17  200:28M                                    Donnelley … Solutions/FA
 4/26/17  Cosan Ltd.                        20-F       12/31/16    7:4.9M                                   Donnelley … Solutions/FA
 7/31/13  Cosan Ltd.                        20-F        3/31/13   10:12M                                    Davis Polk & … LLP 01/FA
 7/31/12  Cosan Ltd.                        20-F        3/31/12    8:7.3M                                   Davis Polk & … LLP 01/FA
 9/30/11  Cosan Ltd.                        20-F        3/31/11   13:10M                                    Davis Polk & … LLP 01/FA
 9/30/10  Cosan Ltd.                        20-F        3/31/10    9:8.8M                                   Davis Polk & … LLP 01/FA
 6/10/09  Cosan Ltd.                        6-K/A       6/10/09    1:741K                                   Davis Polk & … LLP 01/FA
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Filing Submission 0001554855-21-000173   –   Alternative Formats (Word / Rich Text, HTML, Plain Text, et al.)

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