SEC Info  
    Home      Search      My Interests      Help      Sign In      Please Sign In

Originclear, Inc. – ‘10-Q’ for 9/30/23 – ‘EX-101.DEF’

On:  Friday, 12/8/23, at 5:27pm ET   ·   For:  9/30/23   ·   Accession #:  1213900-23-94460   ·   File #:  333-147980

Previous ‘10-Q’:  ‘10-Q’ on 8/25/23 for 6/30/23   ·   Latest ‘10-Q’:  This Filing

Find Words in Filings emoji
 
  in    Show  and   Hints

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

12/08/23  Originclear, Inc.                 10-Q        9/30/23   68:8.3M                                   EdgarAgents LLC/FA

Quarterly Report   —   Form 10-Q

Filing Table of Contents

Document/Exhibit                   Description                      Pages   Size 

 1: 10-Q        Quarterly Report                                    HTML   1.18M 
 2: EX-31.1     Certification -- §302 - SOA'02                      HTML     24K 
 3: EX-31.2     Certification -- §302 - SOA'02                      HTML     24K 
 4: EX-32.1     Certification -- §906 - SOA'02                      HTML     20K 
 5: EX-32.2     Certification -- §906 - SOA'02                      HTML     20K 
11: R1          Document And Entity Information                     HTML     74K 
12: R2          Condensed Consolidated Balance Sheets               HTML    199K 
13: R3          Condensed Consolidated Balance Sheets               HTML    106K 
                (Parentheticals)                                                 
14: R4          Condensed Consolidated Statements of Operations     HTML    104K 
                (Unaudited)                                                      
15: R5          Condensed Consolidated Statements of Operations     HTML     29K 
                (Unaudited) (Parentheticals)                                     
16: R6          Condensed Consolidated Statements of Shareholders?  HTML    221K 
                Deficit                                                          
17: R7          Condensed Consolidated Statements of Cash Flows     HTML    146K 
                (Unaudited)                                                      
18: R8          Basis of Presentation                               HTML     33K 
19: R9          Summary of Significant Accounting Polices           HTML     69K 
20: R10         Capital Stock                                       HTML    100K 
21: R11         Options and Warrants                                HTML     41K 
22: R12         Convertible Promissory Notes                        HTML     46K 
23: R13         Revenue from Contracts with Customers               HTML     32K 
24: R14         Financial Assets                                    HTML     24K 
25: R15         Loans Payable                                       HTML     22K 
26: R16         Water on demand inc.                                HTML     48K 
27: R17         Line of Credit                                      HTML     22K 
28: R18         Assets Held for Sale                                HTML     26K 
29: R19         Employee Retention Tax Credit                       HTML     25K 
30: R20         Commitments and Contingencies                       HTML     27K 
31: R21         Subsequent Events                                   HTML     25K 
32: R22         Accounting Policies, by Policy (Policies)           HTML    108K 
33: R23         Summary of Significant Accounting Polices (Tables)  HTML     53K 
34: R24         Capital Stock (Tables)                              HTML     26K 
35: R25         Options and Warrants (Tables)                       HTML     35K 
36: R26         Convertible Promissory Notes (Tables)               HTML     27K 
37: R27         Revenue from Contracts with Customers (Tables)      HTML     27K 
38: R28         Basis of Presentation (Details)                     HTML     23K 
39: R29         Summary of Significant Accounting Polices           HTML     37K 
                (Details)                                                        
40: R30         Summary of Significant Accounting Polices           HTML     26K 
                (Details) - Schedule of Loss Per Share                           
                Anti-Dilutive Effect                                             
41: R31         Summary of Significant Accounting Polices           HTML     37K 
                (Details) - Schedule of Furniture and Equipment                  
                are Depreciated on the Straight-Line Method                      
42: R32         Summary of Significant Accounting Polices           HTML     42K 
                (Details) - Schedule of Property Plant and                       
                Equipment                                                        
43: R33         Summary of Significant Accounting Polices           HTML     32K 
                (Details) - Schedule of Level Within the Fair                    
                Value Investments and Liabilities                                
44: R34         Summary of Significant Accounting Polices           HTML     25K 
                (Details) - Schedule of Reconciliation of the                    
                Derivative Liability for Which Level 3 inputs                    
45: R35         Summary of Significant Accounting Polices           HTML     34K 
                (Details) - Schedule of Fair Market Value of the                 
                Derivative Liability                                             
46: R36         Capital Stock (Details)                             HTML    866K 
47: R37         Capital Stock (Details) - Schedule of Series A      HTML     33K 
                Preferred Shares                                                 
48: R38         Options and Warrants (Details)                      HTML     70K 
49: R39         Options and Warrants (Details) - Schedule of        HTML     43K 
                Warrant Activity                                                 
50: R40         Options and Warrants (Details) - Schedule of        HTML     52K 
                Weighted Average Remaining Contractual Life of                   
                Warrants Outstanding                                             
51: R41         Convertible Promissory Notes (Details)              HTML    163K 
52: R42         Convertible Promissory Notes (Details) - Schedule   HTML     27K 
                of Outstanding Convertible Promissory Notes                      
53: R43         Convertible Promissory Notes (Details) - Schedule   HTML     31K 
                of Maturities of Long-Term Debt                                  
54: R44         Revenue from Contracts with Customers (Details)     HTML     26K 
55: R45         Revenue from Contracts with Customers (Details) -   HTML     36K 
                Schedule of Good or Service from Contracts with                  
                Customers                                                        
56: R46         Financial Assets (Details)                          HTML     46K 
57: R47         Loans Payable (Details)                             HTML     26K 
58: R48         Water on demand inc. (Details)                      HTML    214K 
59: R49         Line of Credit (Details)                            HTML     30K 
60: R50         Assets Held for Sale (Details)                      HTML     70K 
61: R51         Employee Retention Tax Credit (Details)             HTML     23K 
62: R52         Commitments and Contingencies (Details)             HTML     27K 
63: R53         Subsequent Events (Details)                         HTML     35K 
66: XML         IDEA XML File -- Filing Summary                      XML    123K 
64: XML         XBRL Instance -- f10q0923_originclear_htm            XML   1.54M 
65: EXCEL       IDEA Workbook of Financial Report Info              XLSX    223K 
 7: EX-101.CAL  XBRL Calculations -- ocln-20230930_cal               XML    128K 
 8: EX-101.DEF  XBRL Definitions -- ocln-20230930_def                XML   1.04M 
 9: EX-101.LAB  XBRL Labels -- ocln-20230930_lab                     XML   2.33M 
10: EX-101.PRE  XBRL Presentations -- ocln-20230930_pre              XML   1.02M 
 6: EX-101.SCH  XBRL Schema -- ocln-20230930                         XSD    368K 
67: JSON        XBRL Instance as JSON Data -- MetaLinks              498±   727K 
68: ZIP         XBRL Zipped Folder -- 0001213900-23-094460-xbrl      Zip    535K 


‘EX-101.DEF’   —   XBRL Definitions — ocln-20230930_def


This Exhibit is an XBRL File.


                                                                                                                                                                                
<?xml version="1.0" encoding="windows-1252"?>
<!-- Generated by CompSci Transform (tm) - http://www.compsciresources.com -->
<!-- Created: Fri Dec 08 22:18:10 UTC 2023 -->
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:xbrldt="http://xbrl.org/2005/xbrldt">
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ConsolidatedBalanceSheet" roleURI="http://www.originclear.com/role/ConsolidatedBalanceSheet"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ConsolidatedBalanceSheet_Parentheticals" roleURI="http://www.originclear.com/role/ConsolidatedBalanceSheet_Parentheticals"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ConsolidatedIncomeStatement" roleURI="http://www.originclear.com/role/ConsolidatedIncomeStatement"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ConsolidatedIncomeStatement_Parentheticals" roleURI="http://www.originclear.com/role/ConsolidatedIncomeStatement_Parentheticals"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ShareholdersEquityType2or3" roleURI="http://www.originclear.com/role/ShareholdersEquityType2or3"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ConsolidatedCashFlow" roleURI="http://www.originclear.com/role/ConsolidatedCashFlow"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_BasisofPresentation" roleURI="http://www.originclear.com/role/BasisofPresentation"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_SummaryofSignificantAccountingPolices" roleURI="http://www.originclear.com/role/SummaryofSignificantAccountingPolices"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_CapitalStock" roleURI="http://www.originclear.com/role/CapitalStock"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_OptionsandWarrants" roleURI="http://www.originclear.com/role/OptionsandWarrants"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ConvertiblePromissoryNotes" roleURI="http://www.originclear.com/role/ConvertiblePromissoryNotes"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_RevenuefromContractswithCustomers" roleURI="http://www.originclear.com/role/RevenuefromContractswithCustomers"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_FinancialAssets" roleURI="http://www.originclear.com/role/FinancialAssets"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_LoansPayable" roleURI="http://www.originclear.com/role/LoansPayable"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_Waterondemandinc" roleURI="http://www.originclear.com/role/Waterondemandinc"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_LineofCredit" roleURI="http://www.originclear.com/role/LineofCredit"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_AssetsHeldforSale" roleURI="http://www.originclear.com/role/AssetsHeldforSale"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_EmployeeRetentionTaxCredit" roleURI="http://www.originclear.com/role/EmployeeRetentionTaxCredit"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_CommitmentsandContingencies" roleURI="http://www.originclear.com/role/CommitmentsandContingencies"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_SubsequentEvents" roleURI="http://www.originclear.com/role/SubsequentEvents"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_AccountingPoliciesByPolicy" roleURI="http://www.originclear.com/role/AccountingPoliciesByPolicy"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_SummaryofSignificantAccountingPolicesTables" roleURI="http://www.originclear.com/role/SummaryofSignificantAccountingPolicesTables"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_CapitalStockTables" roleURI="http://www.originclear.com/role/CapitalStockTables"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_OptionsandWarrantsTables" roleURI="http://www.originclear.com/role/OptionsandWarrantsTables"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ConvertiblePromissoryNotesTables" roleURI="http://www.originclear.com/role/ConvertiblePromissoryNotesTables"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_RevenuefromContractswithCustomersTables" roleURI="http://www.originclear.com/role/RevenuefromContractswithCustomersTables"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ScheduleofLossPerShareAntiDilutiveEffectTable" roleURI="http://www.originclear.com/role/ScheduleofLossPerShareAntiDilutiveEffectTable"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ScheduleofFurnitureandEquipmentareDepreciatedontheStraightLineMethodTable" roleURI="http://www.originclear.com/role/ScheduleofFurnitureandEquipmentareDepreciatedontheStraightLineMethodTable"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ScheduleofPropertyPlantandEquipmentTable" roleURI="http://www.originclear.com/role/ScheduleofPropertyPlantandEquipmentTable"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ScheduleofLevelWithintheFairValueInvestmentsandLiabilitiesTable" roleURI="http://www.originclear.com/role/ScheduleofLevelWithintheFairValueInvestmentsandLiabilitiesTable"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ScheduleofReconciliationoftheDerivativeLiabilityforWhichLevel3inputsTable" roleURI="http://www.originclear.com/role/ScheduleofReconciliationoftheDerivativeLiabilityforWhichLevel3inputsTable"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ScheduleofFairMarketValueoftheDerivativeLiabilityTable" roleURI="http://www.originclear.com/role/ScheduleofFairMarketValueoftheDerivativeLiabilityTable"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ScheduleofSeriesAPreferredSharesTable" roleURI="http://www.originclear.com/role/ScheduleofSeriesAPreferredSharesTable"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ScheduleofWarrantActivityTable" roleURI="http://www.originclear.com/role/ScheduleofWarrantActivityTable"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ScheduleofWeightedAverageRemainingContractualLifeofWarrantsOutstandingTable" roleURI="http://www.originclear.com/role/ScheduleofWeightedAverageRemainingContractualLifeofWarrantsOutstandingTable"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ScheduleofOutstandingConvertiblePromissoryNotesTable" roleURI="http://www.originclear.com/role/ScheduleofOutstandingConvertiblePromissoryNotesTable"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ScheduleofMaturitiesofLongTermDebtTable" roleURI="http://www.originclear.com/role/ScheduleofMaturitiesofLongTermDebtTable"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ScheduleofGoodorServicefromContractswithCustomersTable" roleURI="http://www.originclear.com/role/ScheduleofGoodorServicefromContractswithCustomersTable"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_BasisofPresentationDetails" roleURI="http://www.originclear.com/role/BasisofPresentationDetails"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_SummaryofSignificantAccountingPolicesDetails" roleURI="http://www.originclear.com/role/SummaryofSignificantAccountingPolicesDetails"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_CapitalStockDetails" roleURI="http://www.originclear.com/role/CapitalStockDetails"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_OptionsandWarrantsDetails" roleURI="http://www.originclear.com/role/OptionsandWarrantsDetails"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_ConvertiblePromissoryNotesDetails" roleURI="http://www.originclear.com/role/ConvertiblePromissoryNotesDetails"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_RevenuefromContractswithCustomersDetails" roleURI="http://www.originclear.com/role/RevenuefromContractswithCustomersDetails"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_FinancialAssetsDetails" roleURI="http://www.originclear.com/role/FinancialAssetsDetails"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_LoansPayableDetails" roleURI="http://www.originclear.com/role/LoansPayableDetails"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_WaterondemandincDetails" roleURI="http://www.originclear.com/role/WaterondemandincDetails"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_LineofCreditDetails" roleURI="http://www.originclear.com/role/LineofCreditDetails"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_AssetsHeldforSaleDetails" roleURI="http://www.originclear.com/role/AssetsHeldforSaleDetails"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_EmployeeRetentionTaxCreditDetails" roleURI="http://www.originclear.com/role/EmployeeRetentionTaxCreditDetails"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_CommitmentsandContingenciesDetails" roleURI="http://www.originclear.com/role/CommitmentsandContingenciesDetails"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#ocln_r_SubsequentEventsDetails" roleURI="http://www.originclear.com/role/SubsequentEventsDetails"/>
<roleRef xlink:type="simple" xlink:href="ocln-20230930.xsd#DocumentAndEntityInformation" roleURI="http://www.originclear.com/role/DocumentAndEntityInformation"/>
<arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default"/>
<arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain"/>
<arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension"/>
<arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member"/>
<arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" arcroleURI="http://xbrl.org/int/dim/arcrole/all"/>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ConsolidatedBalanceSheet">
<loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementClassOfStockAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementClassOfStockAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesJConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesJConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesJConvertiblePreferredStockMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesLConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesLConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesLConvertiblePreferredStockMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesMreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesMreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesMreferredStockMember" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesO8ConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesO8ConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesO8ConvertiblePreferredStockMember" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesPConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesPConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesPConvertiblePreferredStockMember" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesQ12ConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesQ12ConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesQ12ConvertiblePreferredStockMember" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesR12ConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesR12ConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesR12ConvertiblePreferredStockMember" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesS12ConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesS12ConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesS12ConvertiblePreferredStockMember" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesUConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesUConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesUConvertiblePreferredStockMember" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesW12ConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesW12ConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesW12ConvertiblePreferredStockMember" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesXConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesXConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesXConvertiblePreferredStockMember" order="10" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesYConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesYConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesYConvertiblePreferredStockMember" order="11" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesZConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesZConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesZConvertiblePreferredStockMember" order="12" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesD1PreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesD1PreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesD1PreferredStockMember" order="13" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AssetsCurrentAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsCurrentAbstract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AssetsCurrentAbstract" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_Cash" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Cash"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_Cash" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AccountsReceivableNetCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsReceivableNetCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_AccountsReceivableNetCurrent" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_MarketableSecuritiesCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MarketableSecuritiesCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_MarketableSecuritiesCurrent" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherAssetsCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_OtherAssetsCurrent" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PrepaidExpenseCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrepaidExpenseCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_PrepaidExpenseCurrent" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AssetsCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_AssetsCurrent" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentOtherNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentOtherNet"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentOtherNet" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherAssetsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsAbstract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_OtherAssetsAbstract" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherLongTermInvestments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLongTermInvestments"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherAssetsAbstract" xlink:to="us-gaap_OtherLongTermInvestments" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AccountsReceivableNetNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsReceivableNetNoncurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherAssetsAbstract" xlink:to="us-gaap_AccountsReceivableNetNoncurrent" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonSharesPurchaseCost" xlink:href="ocln-20230930.xsd#ocln_CommonSharesPurchaseCost"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherAssetsAbstract" xlink:to="ocln_CommonSharesPurchaseCost" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_MarketableSecuritiesNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MarketableSecuritiesNoncurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherAssetsAbstract" xlink:to="us-gaap_MarketableSecuritiesNoncurrent" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherIntangibleAssetsNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherIntangibleAssetsNet"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherAssetsAbstract" xlink:to="us-gaap_OtherIntangibleAssetsNet" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssets"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherAssetsAbstract" xlink:to="us-gaap_OtherAssets" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_Assets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Assets"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherAssetsAbstract" xlink:to="us-gaap_Assets" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_LiabilitiesCurrentAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LiabilitiesCurrentAbstract" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AccountsPayableOtherCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsPayableOtherCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_AccountsPayableOtherCurrent" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AccruedLiabilitiesCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_AccruedLiabilitiesCurrent" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CumulativePreferredStockDividendsPayable" xlink:href="ocln-20230930.xsd#ocln_CumulativePreferredStockDividendsPayable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="ocln_CumulativePreferredStockDividendsPayable" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerLiabilityCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerLiabilityCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_ContractWithCustomerLiabilityCurrent" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_TaxesPayableCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TaxesPayableCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_TaxesPayableCurrent" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CustomerDepositCurrent" xlink:href="ocln-20230930.xsd#ocln_CustomerDepositCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="ocln_CustomerDepositCurrent" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WarrantReserveCurrent" xlink:href="ocln-20230930.xsd#ocln_WarrantReserveCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="ocln_WarrantReserveCurrent" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_LinesOfCreditCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LinesOfCreditCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_LinesOfCreditCurrent" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherLoansPayableCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLoansPayableCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_OtherLoansPayableCurrent" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_LoansPayableSBA" xlink:href="ocln-20230930.xsd#ocln_LoansPayableSBA"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="ocln_LoansPayableSBA" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DerivativeLiabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilities"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_DerivativeLiabilities" order="10" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockValue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_PreferredStockValue" order="11" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PreferredStockValue2" xlink:href="ocln-20230930.xsd#ocln_PreferredStockValue2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="ocln_PreferredStockValue2" order="12" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PreferredStockValue3" xlink:href="ocln-20230930.xsd#ocln_PreferredStockValue3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="ocln_PreferredStockValue3" order="13" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PreferredStockValue4" xlink:href="ocln-20230930.xsd#ocln_PreferredStockValue4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="ocln_PreferredStockValue4" order="14" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConvertibleDebtCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertibleDebtCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_ConvertibleDebtCurrent" order="15" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConvertibleNotesPayableCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertibleNotesPayableCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_ConvertibleNotesPayableCurrent" order="16" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_LiabilitiesCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_LiabilitiesCurrent" order="17" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_LongTermLiabilitiesAbstract" xlink:href="ocln-20230930.xsd#ocln_LongTermLiabilitiesAbstract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_LongTermLiabilitiesAbstract" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConvertiblePromissoryNotesNetOfDiscountNetOfTax" xlink:href="ocln-20230930.xsd#ocln_ConvertiblePromissoryNotesNetOfDiscountNetOfTax"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_LongTermLiabilitiesAbstract" xlink:to="ocln_ConvertiblePromissoryNotesNetOfDiscountNetOfTax" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_LiabilitiesOtherThanLongtermDebtNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesOtherThanLongtermDebtNoncurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_LongTermLiabilitiesAbstract" xlink:to="us-gaap_LiabilitiesOtherThanLongtermDebtNoncurrent" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_Liabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Liabilities"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_LongTermLiabilitiesAbstract" xlink:to="us-gaap_Liabilities" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommitmentsAndContingencies" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommitmentsAndContingencies"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommitmentsAndContingencies" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_UnlabeledAbstract14" xlink:href="ocln-20230930.xsd#ocln_UnlabeledAbstract14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_UnlabeledAbstract14" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConvertiblePreferredStock" xlink:href="ocln-20230930.xsd#ocln_ConvertiblePreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_UnlabeledAbstract14" xlink:to="ocln_ConvertiblePreferredStock" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ShareholdersDeficitAbstract" xlink:href="ocln-20230930.xsd#ocln_ShareholdersDeficitAbstract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_ShareholdersDeficitAbstract" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PreferredStockValue7" xlink:href="ocln-20230930.xsd#ocln_PreferredStockValue7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ShareholdersDeficitAbstract" xlink:to="ocln_PreferredStockValue7" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SubscriptionPayableToPurchaseCommonStock" xlink:href="ocln-20230930.xsd#ocln_SubscriptionPayableToPurchaseCommonStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_PreferredStockValue7" xlink:to="ocln_SubscriptionPayableToPurchaseCommonStock" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_TreasuryStockValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockValue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_PreferredStockValue7" xlink:to="us-gaap_TreasuryStockValue" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockValue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_PreferredStockValue7" xlink:to="us-gaap_CommonStockValue" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapitalCommonStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_PreferredStockValue7" xlink:to="us-gaap_AdditionalPaidInCapitalCommonStock" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_PreferredStockValue7" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_PreferredStockValue7" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockholdersEquity" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquity"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_PreferredStockValue7" xlink:to="us-gaap_StockholdersEquity" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_PreferredStockValue7" xlink:to="us-gaap_LiabilitiesAndStockholdersEquity" order="7" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ConsolidatedBalanceSheet_Parentheticals">
<loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementClassOfStockAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementClassOfStockAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesF8PreferredStockTwoMember" xlink:href="ocln-20230930.xsd#ocln_SeriesF8PreferredStockTwoMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesF8PreferredStockTwoMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesG8PreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesG8PreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesG8PreferredStockMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesI8PreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesI8PreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesI8PreferredStockMember" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesK8PreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesK8PreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesK8PreferredStockMember" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesJConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesJConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesJConvertiblePreferredStockMember" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesLConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesLConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesLConvertiblePreferredStockMember" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesMreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesMreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesMreferredStockMember" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesO8ConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesO8ConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesO8ConvertiblePreferredStockMember" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesPConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesPConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesPConvertiblePreferredStockMember" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesQ12ConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesQ12ConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesQ12ConvertiblePreferredStockMember" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesR12ConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesR12ConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesR12ConvertiblePreferredStockMember" order="10" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesS12ConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesS12ConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesS12ConvertiblePreferredStockMember" order="11" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesUConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesUConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesUConvertiblePreferredStockMember" order="12" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesW12ConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesW12ConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesW12ConvertiblePreferredStockMember" order="13" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesXConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesXConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesXConvertiblePreferredStockMember" order="14" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesYConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesYConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesYConvertiblePreferredStockMember" order="15" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesZConvertiblePreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesZConvertiblePreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesZConvertiblePreferredStockMember" order="16" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_PreferredStockMember" order="17" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SeriesAPreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesAPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesAPreferredStockMember" order="18" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SeriesBPreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesBPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesBPreferredStockMember" order="19" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SeriesCPreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesCPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesCPreferredStockMember" order="20" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesD1PreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesD1PreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesD1PreferredStockMember" order="21" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AccountsReceivableNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsReceivableNet"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AccountsReceivableNet" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PreferredStockRedeemableValue" xlink:href="ocln-20230930.xsd#ocln_PreferredStockRedeemableValue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_PreferredStockRedeemableValue" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesIssued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesIssued"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockSharesIssued" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesOutstanding"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockSharesOutstanding" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_LongTermNetOfDiscountCurrent" xlink:href="ocln-20230930.xsd#ocln_LongTermNetOfDiscountCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_LongTermNetOfDiscountCurrent" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConvertiblePreferredStockRedeemableIssuerOptionValues" xlink:href="ocln-20230930.xsd#ocln_ConvertiblePreferredStockRedeemableIssuerOptionValues"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_ConvertiblePreferredStockRedeemableIssuerOptionValues" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConvertiblePreferredStockShareOutstanding" xlink:href="ocln-20230930.xsd#ocln_ConvertiblePreferredStockShareOutstanding"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_ConvertiblePreferredStockShareOutstanding" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesAuthorized" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesAuthorized"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockSharesAuthorized" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockParOrStatedValuePerShare"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockParOrStatedValuePerShare" order="10" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_TreasuryStockPreferredShares" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockPreferredShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_TreasuryStockPreferredShares" order="11" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockParOrStatedValuePerShare" order="12" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesAuthorized" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesAuthorized"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesAuthorized" order="13" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesIssued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesIssued"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesIssued" order="14" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesOutstanding"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesOutstanding" order="15" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ConsolidatedIncomeStatement">
<loc xlink:type="locator" xlink:label="us-gaap_IncomeStatementAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_Revenues" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Revenues"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_Revenues" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CostOfGoodsAndServicesSold" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_CostOfGoodsAndServicesSold" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_GrossProfit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GrossProfit"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_GrossProfit" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OperatingExpensesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingExpensesAbstract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_OperatingExpensesAbstract" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SellingAndMarketingExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SellingAndMarketingExpense"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_SellingAndMarketingExpense" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_GeneralAndAdministrativeExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_GeneralAndAdministrativeExpense" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DepreciationAndAmortization" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DepreciationAndAmortization"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_DepreciationAndAmortization" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OperatingExpenses" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingExpenses"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_OperatingExpenses" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OperatingIncomeLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingIncomeLoss"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_OperatingIncomeLoss" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonoperatingIncomeExpenseAbstract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_NonoperatingIncomeExpenseAbstract" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherNonoperatingIncomeExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_OtherNonoperatingIncomeExpense" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherAssetImpairmentCharges" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetImpairmentCharges"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_OtherAssetImpairmentCharges" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_GainOnWriteOffOfAccountsPayable" xlink:href="ocln-20230930.xsd#ocln_GainOnWriteOffOfAccountsPayable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="ocln_GainOnWriteOffOfAccountsPayable" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_UnrealizedGainlossOnInvestmentSecurities" xlink:href="ocln-20230930.xsd#ocln_UnrealizedGainlossOnInvestmentSecurities"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="ocln_UnrealizedGainlossOnInvestmentSecurities" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_GainLossOnConversionOfPreferredStock" xlink:href="ocln-20230930.xsd#ocln_GainLossOnConversionOfPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="ocln_GainLossOnConversionOfPreferredStock" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockDividendsAndOtherAdjustments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockDividendsAndOtherAdjustments"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_PreferredStockDividendsAndOtherAdjustments" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_UnrealizedGainLossOnDerivatives" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrealizedGainLossOnDerivatives"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_UnrealizedGainLossOnDerivatives" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CashSettlementForNonconversionOfCommonStockinShares" xlink:href="ocln-20230930.xsd#ocln_CashSettlementForNonconversionOfCommonStockinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="ocln_CashSettlementForNonconversionOfCommonStockinShares" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_GainsLossesOnExtinguishmentOfDebt" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_InterestExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpense"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_InterestExpense" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_NonoperatingIncomeExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonoperatingIncomeExpense"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_NonoperatingIncomeExpense" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_NetIncomeLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_NetIncomeLoss" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_EarningsPerShareBasic" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareBasic"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_EarningsPerShareBasic" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WeightedAverageCommonSharesOutstandingAbstract" xlink:href="ocln-20230930.xsd#ocln_WeightedAverageCommonSharesOutstandingAbstract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="ocln_WeightedAverageCommonSharesOutstandingAbstract" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WeightedAverageCommonSharesOutstandingAbstract" xlink:to="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" order="0" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ConsolidatedIncomeStatement_Parentheticals">
<loc xlink:type="locator" xlink:label="us-gaap_IncomeStatementAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_EarningsPerShareDiluted" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareDiluted"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_EarningsPerShareDiluted" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" order="1" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ShareholdersEquityType2or3">
<loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementEquityComponentsAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementEquityComponentsAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_PreferredStockMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_MezzanineEquityMember" xlink:href="ocln-20230930.xsd#ocln_MezzanineEquityMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="ocln_MezzanineEquityMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_CommonStockMember" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AdditionalPaidInCapitalMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AdditionalPaidInCapitalMember" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SubscriptionPayableMember" xlink:href="ocln-20230930.xsd#ocln_SubscriptionPayableMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="ocln_SubscriptionPayableMember" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeMember" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RetainedEarningsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_RetainedEarningsMember" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SharesOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesOutstanding"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_SharesOutstanding" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedThroughARegAToInvestorsForCash" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedThroughARegAToInvestorsForCash"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedThroughARegAToInvestorsForCash" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForCashPerEquityFinancingAgreementinShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForCashPerEquityFinancingAgreementinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForCashPerEquityFinancingAgreementinShares" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedUponConversionOfConvertiblePromissoryNoteinShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedUponConversionOfConvertiblePromissoryNoteinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedUponConversionOfConvertiblePromissoryNoteinShares" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_Rounding" xlink:href="ocln-20230930.xsd#ocln_Rounding"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_Rounding" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_StockIssuedduringPeriodDebtConversionConvertedInstrumentAmount1" xlink:href="ocln-20230930.xsd#ocln_StockIssuedduringPeriodDebtConversionConvertedInstrumentAmount1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_StockIssuedduringPeriodDebtConversionConvertedInstrumentAmount1" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_StockIssuedDuringPeriodDebtConversionConvertedInstrument" xlink:href="ocln-20230930.xsd#ocln_StockIssuedDuringPeriodDebtConversionConvertedInstrument"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_StockIssuedDuringPeriodDebtConversionConvertedInstrument" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_StockIssuedDuringPeriodValueIssuedFairValueforServices" xlink:href="ocln-20230930.xsd#ocln_StockIssuedDuringPeriodValueIssuedFairValueforServices"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_StockIssuedDuringPeriodValueIssuedFairValueforServices" order="10" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_StockIssuedDuringPeriodSharesIssuedFairValueforServices" xlink:href="ocln-20230930.xsd#ocln_StockIssuedDuringPeriodSharesIssuedFairValueforServices"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_StockIssuedDuringPeriodSharesIssuedFairValueforServices" order="11" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesEPreferredStock" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesEPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesEPreferredStock" order="12" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesEPreferredStockinShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesEPreferredStockinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesEPreferredStockinShares" order="13" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesJPreferredStock" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesJPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesJPreferredStock" order="14" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesJPreferredStockinShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesJPreferredStockinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesJPreferredStockinShares" order="15" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesLPreferredStock" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesLPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesLPreferredStock" order="16" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesLPreferredStockShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesLPreferredStockShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesLPreferredStockShares" order="17" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesOPreferredStock" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesOPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesOPreferredStock" order="18" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesOPreferredStockinShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesOPreferredStockinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesOPreferredStockinShares" order="19" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesPPreferredStock" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesPPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesPPreferredStock" order="20" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesPPreferredStockinShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesPPreferredStockinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesPPreferredStockinShares" order="21" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesQPreferredStock" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesQPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesQPreferredStock" order="22" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesQPreferredStockShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesQPreferredStockShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesQPreferredStockShares" order="23" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesRPreferredStock" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesRPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesRPreferredStock" order="24" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesRPreferredStockShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesRPreferredStockShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesRPreferredStockShares" order="25" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesSPreferredStock" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesSPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesSPreferredStock" order="26" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesSPreferredStockinShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesSPreferredStockinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesSPreferredStockinShares" order="27" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesTPreferredStock" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesTPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesTPreferredStock" order="28" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesTPreferredStockinShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesTPreferredStockinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesTPreferredStockinShares" order="29" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesUPreferredStock" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesUPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesUPreferredStock" order="30" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesUPreferredStockinShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesUPreferredStockinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesUPreferredStockinShares" order="31" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesWPreferredStock" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesWPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesWPreferredStock" order="32" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesWPreferredStockinShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesWPreferredStockinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesWPreferredStockinShares" order="33" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesYPreferredStock" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesYPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesYPreferredStock" order="34" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesYPreferredStockinShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesYPreferredStockinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesYPreferredStockinShares" order="35" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesZPreferredStock" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesZPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesZPreferredStock" order="36" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionOfSeriesZPreferredStockinShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionOfSeriesZPreferredStockinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionOfSeriesZPreferredStockinShares" order="37" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForDividendsOnSeriesOPreferredStock" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForDividendsOnSeriesOPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForDividendsOnSeriesOPreferredStock" order="38" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForSeriesOPreferredStockDividendsinShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForSeriesOPreferredStockDividendsinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForSeriesOPreferredStockDividendsinShares" order="39" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionSettlementAgreements" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionSettlementAgreements"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionSettlementAgreements" order="40" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionSettlementAgreementsinShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionSettlementAgreementsinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionSettlementAgreementsinShares" order="41" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueNewIssues" order="42" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesNewIssues" order="43" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_RedemptionOfCommonStockForNotePurchaseAgreement" xlink:href="ocln-20230930.xsd#ocln_RedemptionOfCommonStockForNotePurchaseAgreement"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_RedemptionOfCommonStockForNotePurchaseAgreement" order="44" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_RedemptionOfCommonStockForNotePurchaseAgreementinShares" xlink:href="ocln-20230930.xsd#ocln_RedemptionOfCommonStockForNotePurchaseAgreementinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_RedemptionOfCommonStockForNotePurchaseAgreementinShares" order="45" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_IssuanceOfSeriesBPreferredStockGrantedToInvestors" xlink:href="ocln-20230930.xsd#ocln_IssuanceOfSeriesBPreferredStockGrantedToInvestors"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_IssuanceOfSeriesBPreferredStockGrantedToInvestors" order="46" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_IssuanceOfSeriesAAndBPreferredStockGrantedToSeriesYInvestorsAtFairValueinShares" xlink:href="ocln-20230930.xsd#ocln_IssuanceOfSeriesAAndBPreferredStockGrantedToSeriesYInvestorsAtFairValueinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_IssuanceOfSeriesAAndBPreferredStockGrantedToSeriesYInvestorsAtFairValueinShares" order="47" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueOther" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueOther"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueOther" order="48" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesIssuedForServices" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesIssuedForServices"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesIssuedForServices" order="49" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CancellationOfRegACommonAndSeriesAAndBPreferredShares" xlink:href="ocln-20230930.xsd#ocln_CancellationOfRegACommonAndSeriesAAndBPreferredShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CancellationOfRegACommonAndSeriesAAndBPreferredShares" order="50" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" order="51" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionSeriesQPreferredStockDividends" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionSeriesQPreferredStockDividends"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionSeriesQPreferredStockDividends" order="52" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForConversionSeriesQPreferredStockDividendsinShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForConversionSeriesQPreferredStockDividendsinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForConversionSeriesQPreferredStockDividendsinShares" order="53" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForMakeGoodSharesForSeriesPPreferredStock" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForMakeGoodSharesForSeriesPPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForMakeGoodSharesForSeriesPPreferredStock" order="54" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesOther" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesOther"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesOther" order="55" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForMakeGoodSharesForSeriesRPreferredStock" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForMakeGoodSharesForSeriesRPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForMakeGoodSharesForSeriesRPreferredStock" order="56" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForMakeGoodSharesForSeriesRPreferredStockinShares" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForMakeGoodSharesForSeriesRPreferredStockinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_CommonStockIssuedForMakeGoodSharesForSeriesRPreferredStockinShares" order="57" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfUnits" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfUnits"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueConversionOfUnits" order="58" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesConversionOfUnits" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfUnits"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesConversionOfUnits" order="59" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConversionOfStockAmountIssued1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConversionOfStockAmountIssued1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ConversionOfStockAmountIssued1" order="60" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConversionOfStockSharesIssued1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConversionOfStockSharesIssued1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ConversionOfStockSharesIssued1" order="61" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_IssuanceOfSeriesYPreferredStockThroughAPrivatePlacement" xlink:href="ocln-20230930.xsd#ocln_IssuanceOfSeriesYPreferredStockThroughAPrivatePlacement"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_IssuanceOfSeriesYPreferredStockThroughAPrivatePlacement" order="62" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_IssuanceOfSeriesZPreferredStockThroughAPrivatePlacement" xlink:href="ocln-20230930.xsd#ocln_IssuanceOfSeriesZPreferredStockThroughAPrivatePlacement"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_IssuanceOfSeriesZPreferredStockThroughAPrivatePlacement" order="63" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ExchangeOfSeriesFPreferredStockForSeriesQPreferredStock" xlink:href="ocln-20230930.xsd#ocln_ExchangeOfSeriesFPreferredStockForSeriesQPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_ExchangeOfSeriesFPreferredStockForSeriesQPreferredStock" order="64" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ExchangeOfSeriesIPreferredStockForSeriesWPreferredStock" xlink:href="ocln-20230930.xsd#ocln_ExchangeOfSeriesIPreferredStockForSeriesWPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_ExchangeOfSeriesIPreferredStockForSeriesWPreferredStock" order="65" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ExchangeOfSeriesKPreferredStockForSeriesWPreferredStocks" xlink:href="ocln-20230930.xsd#ocln_ExchangeOfSeriesKPreferredStockForSeriesWPreferredStocks"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_ExchangeOfSeriesKPreferredStockForSeriesWPreferredStocks" order="66" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ExchangeOfSeriesRPreferredStockForWODISecuredConvertibleNote" xlink:href="ocln-20230930.xsd#ocln_ExchangeOfSeriesRPreferredStockForWODISecuredConvertibleNote"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_ExchangeOfSeriesRPreferredStockForWODISecuredConvertibleNote" order="67" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ExchangeOfSeriesXPreferredStockForWODISecuredConvertibleNote" xlink:href="ocln-20230930.xsd#ocln_ExchangeOfSeriesXPreferredStockForWODISecuredConvertibleNote"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_ExchangeOfSeriesXPreferredStockForWODISecuredConvertibleNote" order="68" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConvertiblePreferredStockConvertedToOtherSecurities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertiblePreferredStockConvertedToOtherSecurities"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ConvertiblePreferredStockConvertedToOtherSecurities" order="69" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross" order="70" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesAcquisitions" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesAcquisitions" order="71" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_IssuanceOfCommonStockToInvestorsAfterMerger" xlink:href="ocln-20230930.xsd#ocln_IssuanceOfCommonStockToInvestorsAfterMerger"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_IssuanceOfCommonStockToInvestorsAfterMerger" order="72" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_IssuanceOfCommonStockToInvestorsAfterMergerinShares" xlink:href="ocln-20230930.xsd#ocln_IssuanceOfCommonStockToInvestorsAfterMergerinShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_IssuanceOfCommonStockToInvestorsAfterMergerinShares" order="73" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_LossOnConversionOfPreferredStock" xlink:href="ocln-20230930.xsd#ocln_LossOnConversionOfPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="ocln_LossOnConversionOfPreferredStock" order="74" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_NetIncomeLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_NetIncomeLoss" order="75" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ConsolidatedCashFlow">
<loc xlink:type="locator" xlink:label="us-gaap_StatementOfCashFlowsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementOfCashFlowsAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementOfCashFlowsAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_NetIncomeLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_NetIncomeLoss" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DepreciationDepletionAndAmortization" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_DepreciationDepletionAndAmortization" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PaymentsOfPreferredStockDividends" xlink:href="ocln-20230930.xsd#ocln_PaymentsOfPreferredStockDividends"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="ocln_PaymentsOfPreferredStockDividends" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueAdjustmentOfWarrants" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAdjustmentOfWarrants"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_FairValueAdjustmentOfWarrants" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockDividendsAndOtherAdjustments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockDividendsAndOtherAdjustments"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_PreferredStockDividendsAndOtherAdjustments" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AmortizationOfDebtDiscountPremium" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationOfDebtDiscountPremium"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_AmortizationOfDebtDiscountPremium" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_UnrealizedGainLossOnInvestments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrealizedGainLossOnInvestments"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_UnrealizedGainLossOnInvestments" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ImpairmentOfReceivableFromSPAC" xlink:href="ocln-20230930.xsd#ocln_ImpairmentOfReceivableFromSPAC"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="ocln_ImpairmentOfReceivableFromSPAC" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConversionAndSettlementValueAddedToNotePurchaseAgreements" xlink:href="ocln-20230930.xsd#ocln_ConversionAndSettlementValueAddedToNotePurchaseAgreements"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="ocln_ConversionAndSettlementValueAddedToNotePurchaseAgreements" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_GainLossOnConversionOfPreferredStock" xlink:href="ocln-20230930.xsd#ocln_GainLossOnConversionOfPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="ocln_GainLossOnConversionOfPreferredStock" order="10" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebtBeforeWriteOffOfDeferredDebtIssuanceCost" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebtBeforeWriteOffOfDeferredDebtIssuanceCost"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_GainsLossesOnExtinguishmentOfDebtBeforeWriteOffOfDeferredDebtIssuanceCost" order="11" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInOperatingAssetsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInOperatingAssetsAbstract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_IncreaseDecreaseInOperatingAssetsAbstract" order="12" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingAssetsAbstract" xlink:to="us-gaap_IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInContractWithCustomerAsset" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInContractWithCustomerAsset"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingAssetsAbstract" xlink:to="us-gaap_IncreaseDecreaseInContractWithCustomerAsset" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInInventories" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInInventories"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingAssetsAbstract" xlink:to="us-gaap_IncreaseDecreaseInInventories" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingAssetsAbstract" xlink:to="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInOperatingLiabilitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInOperatingLiabilitiesAbstract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_IncreaseDecreaseInOperatingLiabilitiesAbstract" order="13" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInAccountsPayable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingLiabilitiesAbstract" xlink:to="us-gaap_IncreaseDecreaseInAccountsPayable" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInOtherAccruedLiabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInOtherAccruedLiabilities"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingLiabilitiesAbstract" xlink:to="us-gaap_IncreaseDecreaseInOtherAccruedLiabilities" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInContractWithCustomerLiability" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInContractWithCustomerLiability"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingLiabilitiesAbstract" xlink:to="us-gaap_IncreaseDecreaseInContractWithCustomerLiability" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInDeferredLiabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInDeferredLiabilities"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingLiabilitiesAbstract" xlink:to="us-gaap_IncreaseDecreaseInDeferredLiabilities" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementOfCashFlowsAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivities" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementOfCashFlowsAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireNotesReceivable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireNotesReceivable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="us-gaap_PaymentsToAcquireNotesReceivable" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireOtherInvestments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireOtherInvestments"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="us-gaap_PaymentsToAcquireOtherInvestments" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromSaleOfOtherProductiveAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromSaleOfOtherProductiveAssets"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="us-gaap_ProceedsFromSaleOfOtherProductiveAssets" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireOtherProductiveAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireOtherProductiveAssets"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="us-gaap_PaymentsToAcquireOtherProductiveAssets" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementOfCashFlowsAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivities" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementOfCashFlowsAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RepaymentsOfDebtAndCapitalLeaseObligations" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RepaymentsOfDebtAndCapitalLeaseObligations"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_RepaymentsOfDebtAndCapitalLeaseObligations" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RepaymentsOfNotesPayable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RepaymentsOfNotesPayable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_RepaymentsOfNotesPayable" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromRepaymentsOfLinesOfCredit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromRepaymentsOfLinesOfCredit"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_ProceedsFromRepaymentsOfLinesOfCredit" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_EquityFinancingPurchaseAgreement" xlink:href="ocln-20230930.xsd#ocln_EquityFinancingPurchaseAgreement"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="ocln_EquityFinancingPurchaseAgreement" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PaymentsOnCumulativePreferredStockDividends" xlink:href="ocln-20230930.xsd#ocln_PaymentsOnCumulativePreferredStockDividends"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="ocln_PaymentsOnCumulativePreferredStockDividends" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfOtherLongTermDebt" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromIssuanceOfOtherLongTermDebt"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_ProceedsFromIssuanceOfOtherLongTermDebt" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedForRegAForCash" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedForRegAForCash"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="ocln_CommonStockIssuedForRegAForCash" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonStock" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_NetProceedsForIssuanceOfPreferredStockForCashLiabilityClassification" xlink:href="ocln-20230930.xsd#ocln_NetProceedsForIssuanceOfPreferredStockForCashLiabilityClassification"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="ocln_NetProceedsForIssuanceOfPreferredStockForCashLiabilityClassification" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementOfCashFlowsAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivities" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementOfCashFlowsAbstract" xlink:to="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementOfCashFlowsAbstract" xlink:to="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SupplementalCashFlowInformationAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SupplementalCashFlowInformationAbstract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementOfCashFlowsAbstract" xlink:to="us-gaap_SupplementalCashFlowInformationAbstract" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_InterestPaidNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestPaidNet"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SupplementalCashFlowInformationAbstract" xlink:to="us-gaap_InterestPaidNet" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_IncomeTaxesPaidNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxesPaidNet"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SupplementalCashFlowInformationAbstract" xlink:to="us-gaap_IncomeTaxesPaidNet" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_NoncashInvestingAndFinancingItemsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncashInvestingAndFinancingItemsAbstract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementOfCashFlowsAbstract" xlink:to="us-gaap_NoncashInvestingAndFinancingItemsAbstract" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockIssuedAtFairValueForConversionOfDebtPlusAccruedInterestAndOtherFees" xlink:href="ocln-20230930.xsd#ocln_CommonStockIssuedAtFairValueForConversionOfDebtPlusAccruedInterestAndOtherFees"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NoncashInvestingAndFinancingItemsAbstract" xlink:to="ocln_CommonStockIssuedAtFairValueForConversionOfDebtPlusAccruedInterestAndOtherFees" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_IssuanceOfWarrantsDeemedDividends" xlink:href="ocln-20230930.xsd#ocln_IssuanceOfWarrantsDeemedDividends"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NoncashInvestingAndFinancingItemsAbstract" xlink:to="ocln_IssuanceOfWarrantsDeemedDividends" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PreferredStockConvertedToCommonStockEquity" xlink:href="ocln-20230930.xsd#ocln_PreferredStockConvertedToCommonStockEquity"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NoncashInvestingAndFinancingItemsAbstract" xlink:to="ocln_PreferredStockConvertedToCommonStockEquity" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_IssuanceOfSeriesRPreferredStockForWODISecuredConvertibleNote" xlink:href="ocln-20230930.xsd#ocln_IssuanceOfSeriesRPreferredStockForWODISecuredConvertibleNote"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NoncashInvestingAndFinancingItemsAbstract" xlink:to="ocln_IssuanceOfSeriesRPreferredStockForWODISecuredConvertibleNote" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ExchangeOfSeriesXPreferredStockForWODISecuredConvertibleNotes" xlink:href="ocln-20230930.xsd#ocln_ExchangeOfSeriesXPreferredStockForWODISecuredConvertibleNotes"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NoncashInvestingAndFinancingItemsAbstract" xlink:to="ocln_ExchangeOfSeriesXPreferredStockForWODISecuredConvertibleNotes" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ExchangeFromMezzanineToLiability" xlink:href="ocln-20230930.xsd#ocln_ExchangeFromMezzanineToLiability"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NoncashInvestingAndFinancingItemsAbstract" xlink:to="ocln_ExchangeFromMezzanineToLiability" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockIssued1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssued1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NoncashInvestingAndFinancingItemsAbstract" xlink:to="us-gaap_StockIssued1" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ShareIssued" xlink:href="ocln-20230930.xsd#ocln_ShareIssued"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NoncashInvestingAndFinancingItemsAbstract" xlink:to="ocln_ShareIssued" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_IssuanceOfPWTCommonStockToWODIShareholders" xlink:href="ocln-20230930.xsd#ocln_IssuanceOfPWTCommonStockToWODIShareholders"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NoncashInvestingAndFinancingItemsAbstract" xlink:to="ocln_IssuanceOfPWTCommonStockToWODIShareholders" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_RedemptionOfSharesForSecuredPromissoryNotes" xlink:href="ocln-20230930.xsd#ocln_RedemptionOfSharesForSecuredPromissoryNotes"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NoncashInvestingAndFinancingItemsAbstract" xlink:to="ocln_RedemptionOfSharesForSecuredPromissoryNotes" order="9" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/BasisofPresentation">
<loc xlink:type="locator" xlink:label="us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_BusinessDescriptionAndBasisOfPresentationTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessDescriptionAndBasisOfPresentationTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:to="us-gaap_BusinessDescriptionAndBasisOfPresentationTextBlock" order="0" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/SummaryofSignificantAccountingPolices">
<loc xlink:type="locator" xlink:label="us-gaap_AccountingPoliciesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountingPoliciesAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_SignificantAccountingPoliciesTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SignificantAccountingPoliciesTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_SignificantAccountingPoliciesTextBlock" order="0" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/CapitalStock">
<loc xlink:type="locator" xlink:label="us-gaap_StockholdersEquityNoteAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityNoteAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityNoteDisclosureTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityNoteAbstract" xlink:to="us-gaap_StockholdersEquityNoteDisclosureTextBlock" order="0" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/OptionsandWarrants">
<loc xlink:type="locator" xlink:label="ocln_OptionsAndWarrantsAbstract" xlink:href="ocln-20230930.xsd#ocln_OptionsAndWarrantsAbstract"/>
<loc xlink:type="locator" xlink:label="ocln_OptionsAndWarrantsTextBlock" xlink:href="ocln-20230930.xsd#ocln_OptionsAndWarrantsTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsAndWarrantsAbstract" xlink:to="ocln_OptionsAndWarrantsTextBlock" order="0" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ConvertiblePromissoryNotes">
<loc xlink:type="locator" xlink:label="us-gaap_ConvertibleLongtermNotesPayableCurrentAndNoncurrentAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertibleLongtermNotesPayableCurrentAndNoncurrentAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_DebtDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtDisclosureTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConvertibleLongtermNotesPayableCurrentAndNoncurrentAbstract" xlink:to="us-gaap_DebtDisclosureTextBlock" order="0" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/RevenuefromContractswithCustomers">
<loc xlink:type="locator" xlink:label="us-gaap_RevenueFromContractWithCustomerAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_RevenueFromContractWithCustomerTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RevenueFromContractWithCustomerAbstract" xlink:to="us-gaap_RevenueFromContractWithCustomerTextBlock" order="0" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/FinancialAssets">
<loc xlink:type="locator" xlink:label="us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_IntangibleAssetsDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntangibleAssetsDisclosureTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:to="us-gaap_IntangibleAssetsDisclosureTextBlock" order="0" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/LoansPayable">
<loc xlink:type="locator" xlink:label="ocln_LoansPayableLineItems" xlink:href="ocln-20230930.xsd#ocln_LoansPayableLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_LoansPayableTable" xlink:href="ocln-20230930.xsd#ocln_LoansPayableTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_LoansPayableLineItems" xlink:to="ocln_LoansPayableTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_LoansPayableDisclosureTextBlock" xlink:href="ocln-20230930.xsd#ocln_LoansPayableDisclosureTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_LoansPayableLineItems" xlink:to="ocln_LoansPayableDisclosureTextBlock" order="1" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/Waterondemandinc">
<loc xlink:type="locator" xlink:label="ocln_WaterondemandincLineItems" xlink:href="ocln-20230930.xsd#ocln_WaterondemandincLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_WaterondemandincTable" xlink:href="ocln-20230930.xsd#ocln_WaterondemandincTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_WaterondemandincLineItems" xlink:to="ocln_WaterondemandincTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_DisclosureOfWaterOnDemandIncTextBlock" xlink:href="ocln-20230930.xsd#ocln_DisclosureOfWaterOnDemandIncTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincLineItems" xlink:to="ocln_DisclosureOfWaterOnDemandIncTextBlock" order="1" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/LineofCredit">
<loc xlink:type="locator" xlink:label="ocln_LineofCreditLineItems" xlink:href="ocln-20230930.xsd#ocln_LineofCreditLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_LineofCreditTable" xlink:href="ocln-20230930.xsd#ocln_LineofCreditTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_LineofCreditLineItems" xlink:to="ocln_LineofCreditTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShortTermDebtTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_LineofCreditLineItems" xlink:to="us-gaap_ShortTermDebtTextBlock" order="1" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/AssetsHeldforSale">
<loc xlink:type="locator" xlink:label="us-gaap_AssetsHeldForSaleNotPartOfDisposalGroupCurrentAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsHeldForSaleNotPartOfDisposalGroupCurrentAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_DisclosureOfLongLivedAssetsHeldForSaleTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisclosureOfLongLivedAssetsHeldForSaleTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsHeldForSaleNotPartOfDisposalGroupCurrentAbstract" xlink:to="us-gaap_DisclosureOfLongLivedAssetsHeldForSaleTextBlock" order="0" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/EmployeeRetentionTaxCredit">
<loc xlink:type="locator" xlink:label="us-gaap_IncomeTaxDisclosureAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxDisclosureAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_IncomeTaxDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxDisclosureTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeTaxDisclosureAbstract" xlink:to="us-gaap_IncomeTaxDisclosureTextBlock" order="0" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/CommitmentsandContingencies">
<loc xlink:type="locator" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommitmentsAndContingenciesDisclosureAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommitmentsAndContingenciesDisclosureTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:to="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" order="0" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/SubsequentEvents">
<loc xlink:type="locator" xlink:label="ocln_SubsequentEventsLineItems" xlink:href="ocln-20230930.xsd#ocln_SubsequentEventsLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_SubsequentEventsTable" xlink:href="ocln-20230930.xsd#ocln_SubsequentEventsTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_SubsequentEventsLineItems" xlink:to="ocln_SubsequentEventsTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SubsequentEventsTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventsTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_SubsequentEventsLineItems" xlink:to="us-gaap_SubsequentEventsTextBlock" order="1" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/AccountingPoliciesByPolicy">
<loc xlink:type="locator" xlink:label="us-gaap_AccountingPoliciesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountingPoliciesAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConsolidationPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConsolidationPolicyTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_ConsolidationPolicyTextBlock" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsPolicyTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_CashAndCashEquivalentsPolicyTextBlock" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_UseOfEstimates" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UseOfEstimates"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_UseOfEstimates" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_EarningsPerSharePolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerSharePolicyTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_EarningsPerSharePolicyTextBlock" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RevenueRecognitionPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRecognitionPolicyTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_RevenueRecognitionPolicyTextBlock" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ReceivablesPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivablesPolicyTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_ReceivablesPolicyTextBlock" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_GoodwillAndIntangibleAssetsIntangibleAssetsIndefiniteLivedPolicy" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillAndIntangibleAssetsIntangibleAssetsIndefiniteLivedPolicy"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_GoodwillAndIntangibleAssetsIntangibleAssetsIndefiniteLivedPolicy" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PrepaidExpensesPolicyTextBlock" xlink:href="ocln-20230930.xsd#ocln_PrepaidExpensesPolicyTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="ocln_PrepaidExpensesPolicyTextBlock" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentPolicyTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DerivativesPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativesPolicyTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_DerivativesPolicyTextBlock" order="10" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementPolicyPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementPolicyPolicyTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_FairValueMeasurementPolicyPolicyTextBlock" order="11" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SegmentReportingPolicyPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingPolicyPolicyTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_SegmentReportingPolicyPolicyTextBlock" order="12" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_MarketableSecuritiesPolicy" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MarketableSecuritiesPolicy"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_MarketableSecuritiesPolicy" order="13" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_RevenueRecognitionLicensingFeesPolicyTextBlock" xlink:href="ocln-20230930.xsd#ocln_RevenueRecognitionLicensingFeesPolicyTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="ocln_RevenueRecognitionLicensingFeesPolicyTextBlock" order="14" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PriorPeriodReclassificationAdjustmentDescription" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PriorPeriodReclassificationAdjustmentDescription"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_PriorPeriodReclassificationAdjustmentDescription" order="15" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_InventoryWorkInProcessPolicy" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryWorkInProcessPolicy"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_InventoryWorkInProcessPolicy" order="16" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" order="17" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/SummaryofSignificantAccountingPolicesTables">
<loc xlink:type="locator" xlink:label="us-gaap_AccountingPoliciesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountingPoliciesAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ScheduleOfFurnitureAndEquipmentAreDepreciatedOnTheStraightlineMethodtableTextBlock" xlink:href="ocln-20230930.xsd#ocln_ScheduleOfFurnitureAndEquipmentAreDepreciatedOnTheStraightlineMethodtableTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="ocln_ScheduleOfFurnitureAndEquipmentAreDepreciatedOnTheStraightlineMethodtableTextBlock" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_PropertyPlantAndEquipmentTextBlock" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfAssumptionsUsedTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAssumptionsUsedTableTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_ScheduleOfAssumptionsUsedTableTextBlock" order="5" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/CapitalStockTables">
<loc xlink:type="locator" xlink:label="us-gaap_StockholdersEquityNoteAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityNoteAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfAuctionMarketPreferredSecuritiesByStockSeriesTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAuctionMarketPreferredSecuritiesByStockSeriesTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityNoteAbstract" xlink:to="us-gaap_ScheduleOfAuctionMarketPreferredSecuritiesByStockSeriesTextBlock" order="0" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/OptionsandWarrantsTables">
<loc xlink:type="locator" xlink:label="ocln_OptionsAndWarrantsAbstract" xlink:href="ocln-20230930.xsd#ocln_OptionsAndWarrantsAbstract"/>
<loc xlink:type="locator" xlink:label="ocln_ScheduleOfWarrantActivityTableTextBlock" xlink:href="ocln-20230930.xsd#ocln_ScheduleOfWarrantActivityTableTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsAndWarrantsAbstract" xlink:to="ocln_ScheduleOfWarrantActivityTableTextBlock" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfStockholdersEquityNoteWarrantsOrRightsTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfStockholdersEquityNoteWarrantsOrRightsTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsAndWarrantsAbstract" xlink:to="us-gaap_ScheduleOfStockholdersEquityNoteWarrantsOrRightsTextBlock" order="1" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ConvertiblePromissoryNotesTables">
<loc xlink:type="locator" xlink:label="us-gaap_ConvertibleLongtermNotesPayableCurrentAndNoncurrentAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertibleLongtermNotesPayableCurrentAndNoncurrentAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConvertibleDebtTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertibleDebtTableTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConvertibleLongtermNotesPayableCurrentAndNoncurrentAbstract" xlink:to="us-gaap_ConvertibleDebtTableTextBlock" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConvertibleLongtermNotesPayableCurrentAndNoncurrentAbstract" xlink:to="us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock" order="1" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/RevenuefromContractswithCustomersTables">
<loc xlink:type="locator" xlink:label="us-gaap_RevenueFromContractWithCustomerAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_DisaggregationOfRevenueTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueTableTextBlock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RevenueFromContractWithCustomerAbstract" xlink:to="us-gaap_DisaggregationOfRevenueTableTextBlock" order="0" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ScheduleofLossPerShareAntiDilutiveEffectTable">
<loc xlink:type="locator" xlink:label="ocln_ScheduleOfLossPerShareAntiDilutiveEffectAbstract" xlink:href="ocln-20230930.xsd#ocln_ScheduleOfLossPerShareAntiDilutiveEffectAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_NetIncomeLossFromDiscontinuedOperationsAvailableToCommonShareholdersBasic" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLossFromDiscontinuedOperationsAvailableToCommonShareholdersBasic"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfLossPerShareAntiDilutiveEffectAbstract" xlink:to="us-gaap_NetIncomeLossFromDiscontinuedOperationsAvailableToCommonShareholdersBasic" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_BasicWeightedAverageNumberOfCommonSharesOutstandingDenominator" xlink:href="ocln-20230930.xsd#ocln_BasicWeightedAverageNumberOfCommonSharesOutstandingDenominator"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfLossPerShareAntiDilutiveEffectAbstract" xlink:to="ocln_BasicWeightedAverageNumberOfCommonSharesOutstandingDenominator" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfLossPerShareAntiDilutiveEffectAbstract" xlink:to="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" order="2" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ScheduleofFurnitureandEquipmentareDepreciatedontheStraightLineMethodTable">
<loc xlink:type="locator" xlink:label="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFurnitureandEquipmentareDepreciatedontheStraightLineMethodLineItems" xlink:href="ocln-20230930.xsd#ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFurnitureandEquipmentareDepreciatedontheStraightLineMethodLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFurnitureandEquipmentareDepreciatedontheStraightLineMethodTable" xlink:href="ocln-20230930.xsd#ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFurnitureandEquipmentareDepreciatedontheStraightLineMethodTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFurnitureandEquipmentareDepreciatedontheStraightLineMethodLineItems" xlink:to="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFurnitureandEquipmentareDepreciatedontheStraightLineMethodTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFurnitureandEquipmentareDepreciatedontheStraightLineMethodTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFurnitureandEquipmentareDepreciatedontheStraightLineMethodTable" xlink:to="srt_RangeAxis" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeMember_0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_MinimumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_MaximumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_MachineryAndEquipmentMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MachineryAndEquipmentMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_MachineryAndEquipmentMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FurnitureAndFixturesMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FurnitureAndFixturesMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_FurnitureAndFixturesMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_VehiclesMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VehiclesMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_VehiclesMember" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_LandAndLandImprovementsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LandAndLandImprovementsMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_LandAndLandImprovementsMember" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFurnitureandEquipmentareDepreciatedontheStraightLineMethodLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentUsefulLife" order="1" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ScheduleofPropertyPlantandEquipmentTable">
<loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
<loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_MachineryAndEquipmentMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MachineryAndEquipmentMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_MachineryAndEquipmentMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ComputerEquipmentMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ComputerEquipmentMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_ComputerEquipmentMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FurnitureAndFixturesMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FurnitureAndFixturesMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_FurnitureAndFixturesMember" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_LeaseholdImprovementsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LeaseholdImprovementsMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_LeaseholdImprovementsMember" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_VehiclesMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VehiclesMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_VehiclesMember" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_DemoUnitsMember" xlink:href="ocln-20230930.xsd#ocln_DemoUnitsMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="ocln_DemoUnitsMember" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentGross" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentGross" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentNet" order="3" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ScheduleofLevelWithintheFairValueInvestmentsandLiabilitiesTable">
<loc xlink:type="locator" xlink:label="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofLevelWithintheFairValueInvestmentsandLiabilitiesLineItems" xlink:href="ocln-20230930.xsd#ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofLevelWithintheFairValueInvestmentsandLiabilitiesLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofLevelWithintheFairValueInvestmentsandLiabilitiesTable" xlink:href="ocln-20230930.xsd#ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofLevelWithintheFairValueInvestmentsandLiabilitiesTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofLevelWithintheFairValueInvestmentsandLiabilitiesLineItems" xlink:to="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofLevelWithintheFairValueInvestmentsandLiabilitiesTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofLevelWithintheFairValueInvestmentsandLiabilitiesTable" xlink:to="us-gaap_FairValueByFairValueHierarchyLevelAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel1Member" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel1Member"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel1Member" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel2Member" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel2Member"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel2Member" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel3Member" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel3Member" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueNetAssetLiability" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetAssetLiability"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofLevelWithintheFairValueInvestmentsandLiabilitiesLineItems" xlink:to="us-gaap_FairValueNetAssetLiability" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofLevelWithintheFairValueInvestmentsandLiabilitiesLineItems" xlink:to="us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet" order="2" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ScheduleofReconciliationoftheDerivativeLiabilityforWhichLevel3inputsTable">
<loc xlink:type="locator" xlink:label="ocln_ScheduleOfReconciliationOfTheDerivativeLiabilityForWhichLevel3InputsAbstract" xlink:href="ocln-20230930.xsd#ocln_ScheduleOfReconciliationOfTheDerivativeLiabilityForWhichLevel3InputsAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfReconciliationOfTheDerivativeLiabilityForWhichLevel3InputsAbstract" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_NetLossGainOnConversionOfDebtAndChangeInDerivativeLiability" xlink:href="ocln-20230930.xsd#ocln_NetLossGainOnConversionOfDebtAndChangeInDerivativeLiability"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfReconciliationOfTheDerivativeLiabilityForWhichLevel3InputsAbstract" xlink:to="ocln_NetLossGainOnConversionOfDebtAndChangeInDerivativeLiability" order="1" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ScheduleofFairMarketValueoftheDerivativeLiabilityTable">
<loc xlink:type="locator" xlink:label="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFairMarketValueoftheDerivativeLiabilityLineItems" xlink:href="ocln-20230930.xsd#ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFairMarketValueoftheDerivativeLiabilityLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFairMarketValueoftheDerivativeLiabilityTable" xlink:href="ocln-20230930.xsd#ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFairMarketValueoftheDerivativeLiabilityTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFairMarketValueoftheDerivativeLiabilityLineItems" xlink:to="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFairMarketValueoftheDerivativeLiabilityTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFairMarketValueoftheDerivativeLiabilityTable" xlink:to="srt_RangeAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeMember_0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_MinimumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_MaximumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFairMarketValueoftheDerivativeLiabilityLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFairMarketValueoftheDerivativeLiabilityLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFairMarketValueoftheDerivativeLiabilityLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_SummaryofSignificantAccountingPolicesDetailsScheduleofFairMarketValueoftheDerivativeLiabilityLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" order="4" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ScheduleofSeriesAPreferredSharesTable">
<loc xlink:type="locator" xlink:label="us-gaap_AuctionMarketPreferredSecuritiesStockSeriesLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AuctionMarketPreferredSecuritiesStockSeriesLineItems"/>
<loc xlink:type="locator" xlink:label="us-gaap_AuctionMarketPreferredSecuritiesStockSeriesTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AuctionMarketPreferredSecuritiesStockSeriesTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_AuctionMarketPreferredSecuritiesStockSeriesLineItems" xlink:to="us-gaap_AuctionMarketPreferredSecuritiesStockSeriesTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementEquityComponentsAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_AuctionMarketPreferredSecuritiesStockSeriesTable" xlink:to="us-gaap_StatementEquityComponentsAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_December282022Member" xlink:href="ocln-20230930.xsd#ocln_December282022Member"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="ocln_December282022Member" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_February082023Member" xlink:href="ocln-20230930.xsd#ocln_February082023Member"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="ocln_February082023Member" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_June152023Member" xlink:href="ocln-20230930.xsd#ocln_June152023Member"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="ocln_June152023Member" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_August212023Member" xlink:href="ocln-20230930.xsd#ocln_August212023Member"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="ocln_August212023Member" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_June272023Member" xlink:href="ocln-20230930.xsd#ocln_June272023Member"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="ocln_June272023Member" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AuctionMarketPreferredSecuritiesStockSeriesLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" order="1" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ScheduleofWarrantActivityTable">
<loc xlink:type="locator" xlink:label="ocln_OptionsandWarrantsDetailsScheduleofWarrantActivityLineItems" xlink:href="ocln-20230930.xsd#ocln_OptionsandWarrantsDetailsScheduleofWarrantActivityLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_OptionsandWarrantsDetailsScheduleofWarrantActivityTable" xlink:href="ocln-20230930.xsd#ocln_OptionsandWarrantsDetailsScheduleofWarrantActivityTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_OptionsandWarrantsDetailsScheduleofWarrantActivityLineItems" xlink:to="ocln_OptionsandWarrantsDetailsScheduleofWarrantActivityTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_OptionsandWarrantsDetailsScheduleofWarrantActivityTable" xlink:to="us-gaap_ClassOfWarrantOrRightAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ClassOfWarrantOrRightAxis" xlink:to="us-gaap_ClassOfWarrantOrRightDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ClassOfWarrantOrRightAxis" xlink:to="us-gaap_ClassOfWarrantOrRightDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_WarrantMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WarrantMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain" xlink:to="us-gaap_WarrantMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WeightedAverageExercisePriceMember" xlink:href="ocln-20230930.xsd#ocln_WeightedAverageExercisePriceMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain" xlink:to="ocln_WeightedAverageExercisePriceMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsScheduleofWarrantActivityLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsScheduleofWarrantActivityLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsScheduleofWarrantActivityLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsScheduleofWarrantActivityLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsScheduleofWarrantActivityLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsScheduleofWarrantActivityLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsScheduleofWarrantActivityLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsScheduleofWarrantActivityLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice" order="8" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ScheduleofWeightedAverageRemainingContractualLifeofWarrantsOutstandingTable">
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightLineItems"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ClassOfWarrantOrRightTable" xlink:to="srt_RangeAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeMember_0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SubsidiarySaleOfStockAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ClassOfWarrantOrRightTable" xlink:to="us-gaap_SubsidiarySaleOfStockAxis" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SaleOfStockNameOfTransactionDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_SubsidiarySaleOfStockAxis" xlink:to="us-gaap_SaleOfStockNameOfTransactionDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SaleOfStockNameOfTransactionDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_SubsidiarySaleOfStockAxis" xlink:to="us-gaap_SaleOfStockNameOfTransactionDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_MinimumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_MaximumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_WarrantMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WarrantMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SaleOfStockNameOfTransactionDomain" xlink:to="us-gaap_WarrantMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WarrantTwoMember" xlink:href="ocln-20230930.xsd#ocln_WarrantTwoMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SaleOfStockNameOfTransactionDomain" xlink:to="ocln_WarrantTwoMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WarrantThreeMember" xlink:href="ocln-20230930.xsd#ocln_WarrantThreeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SaleOfStockNameOfTransactionDomain" xlink:to="ocln_WarrantThreeMember" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WarrantFourMember" xlink:href="ocln-20230930.xsd#ocln_WarrantFourMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SaleOfStockNameOfTransactionDomain" xlink:to="ocln_WarrantFourMember" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WarrantFiveMember" xlink:href="ocln-20230930.xsd#ocln_WarrantFiveMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SaleOfStockNameOfTransactionDomain" xlink:to="ocln_WarrantFiveMember" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WarrantSixMember" xlink:href="ocln-20230930.xsd#ocln_WarrantSixMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SaleOfStockNameOfTransactionDomain" xlink:to="ocln_WarrantSixMember" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightOutstanding"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightOutstanding" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableWarrants" xlink:href="ocln-20230930.xsd#ocln_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableWarrants"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="ocln_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableWarrants" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WeightedAverageRemainingContractualLifeyears" xlink:href="ocln-20230930.xsd#ocln_WeightedAverageRemainingContractualLifeyears"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="ocln_WeightedAverageRemainingContractualLifeyears" order="4" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ScheduleofOutstandingConvertiblePromissoryNotesTable">
<loc xlink:type="locator" xlink:label="ocln_ScheduleOfOutstandingConvertiblePromissoryNotesAbstract" xlink:href="ocln-20230930.xsd#ocln_ScheduleOfOutstandingConvertiblePromissoryNotesAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConvertibleNotesPayable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertibleNotesPayable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfOutstandingConvertiblePromissoryNotesAbstract" xlink:to="us-gaap_ConvertibleNotesPayable" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherLongTermDebtCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLongTermDebtCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfOutstandingConvertiblePromissoryNotesAbstract" xlink:to="us-gaap_OtherLongTermDebtCurrent" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConvertiblePromissoryNotes" xlink:href="ocln-20230930.xsd#ocln_ConvertiblePromissoryNotes"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfOutstandingConvertiblePromissoryNotesAbstract" xlink:to="ocln_ConvertiblePromissoryNotes" order="2" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ScheduleofMaturitiesofLongTermDebtTable"> <!-- [WMV5][XcpuxYn59dz7vgYynUDuwG7r97K2jUTysl7vcz0lJt/tSeJz73kx1cLt0ZFF2SK/vxBCY0vdSrbT+zA71yx8y/GPitNzif6WXL0fv7uXBoKB/RGz89EKxGiSvNr71YkvlSao2qvRAL2+CLVYEt/TKdWEHkFEh9JjMFpfG4y4xDYno2uQMVuDqYUUHlcGFF6EPWKVT7PdQOUbeL8ogXm1JoiM/gH3quNnre/f2jPAzj4I68vZhQ5aC98utXkLTUQNbEE3YJZiWpoAlnuDG6+ssQ==] CSR -->
<loc xlink:type="locator" xlink:label="ocln_ScheduleOfMaturitiesOfLongTermDebtAbstract" xlink:href="ocln-20230930.xsd#ocln_ScheduleOfMaturitiesOfLongTermDebtAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfMaturitiesOfLongTermDebtAbstract" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfMaturitiesOfLongTermDebtAbstract" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfMaturitiesOfLongTermDebtAbstract" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfMaturitiesOfLongTermDebtAbstract" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfMaturitiesOfLongTermDebtAbstract" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" order="4" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ScheduleofGoodorServicefromContractswithCustomersTable">
<loc xlink:type="locator" xlink:label="ocln_ScheduleOfGoodOrServiceFromContractsWithCustomersAbstract" xlink:href="ocln-20230930.xsd#ocln_ScheduleOfGoodOrServiceFromContractsWithCustomersAbstract"/>
<loc xlink:type="locator" xlink:label="ocln_RevenueFromEquipmentContracts" xlink:href="ocln-20230930.xsd#ocln_RevenueFromEquipmentContracts"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfGoodOrServiceFromContractsWithCustomersAbstract" xlink:to="ocln_RevenueFromEquipmentContracts" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ComponentSales" xlink:href="ocln-20230930.xsd#ocln_ComponentSales"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfGoodOrServiceFromContractsWithCustomersAbstract" xlink:to="ocln_ComponentSales" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WasteWaterTreatmentSystems" xlink:href="ocln-20230930.xsd#ocln_WasteWaterTreatmentSystems"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfGoodOrServiceFromContractsWithCustomersAbstract" xlink:to="ocln_WasteWaterTreatmentSystems" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PumpStations" xlink:href="ocln-20230930.xsd#ocln_PumpStations"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfGoodOrServiceFromContractsWithCustomersAbstract" xlink:to="ocln_PumpStations" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RentalIncomeNonoperating" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RentalIncomeNonoperating"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfGoodOrServiceFromContractsWithCustomersAbstract" xlink:to="us-gaap_RentalIncomeNonoperating" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_RevenueFromServicesSales" xlink:href="ocln-20230930.xsd#ocln_RevenueFromServicesSales"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfGoodOrServiceFromContractsWithCustomersAbstract" xlink:to="ocln_RevenueFromServicesSales" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_RevenueFromInternetSales" xlink:href="ocln-20230930.xsd#ocln_RevenueFromInternetSales"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfGoodOrServiceFromContractsWithCustomersAbstract" xlink:to="ocln_RevenueFromInternetSales" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommissionTraining" xlink:href="ocln-20230930.xsd#ocln_CommissionTraining"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfGoodOrServiceFromContractsWithCustomersAbstract" xlink:to="ocln_CommissionTraining" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherCostOfOperatingRevenue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCostOfOperatingRevenue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ScheduleOfGoodOrServiceFromContractsWithCustomersAbstract" xlink:to="us-gaap_OtherCostOfOperatingRevenue" order="8" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/BasisofPresentationDetails">
<loc xlink:type="locator" xlink:label="us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract"/>
<loc xlink:type="locator" xlink:label="ocln_AggregateFundingAmount" xlink:href="ocln-20230930.xsd#ocln_AggregateFundingAmount"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:to="ocln_AggregateFundingAmount" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SaleRevenueNet" xlink:href="ocln-20230930.xsd#ocln_SaleRevenueNet"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:to="ocln_SaleRevenueNet" order="1" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/SummaryofSignificantAccountingPolicesDetails">
<loc xlink:type="locator" xlink:label="us-gaap_AccountingPoliciesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountingPoliciesAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivableNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableNoncurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_AllowanceForDoubtfulAccountsReceivableNoncurrent" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_OtherReceivableAmount" xlink:href="ocln-20230930.xsd#ocln_OtherReceivableAmount"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="ocln_OtherReceivableAmount" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PrepaidExpenseCurrentAndNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrepaidExpenseCurrentAndNoncurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_PrepaidExpenseCurrentAndNoncurrent" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_Depreciation" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Depreciation"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_Depreciation" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DerivativeTermOfContract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeTermOfContract"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_DerivativeTermOfContract" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsAndHedgesLiabilitiesNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsAndHedgesLiabilitiesNoncurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_DerivativeInstrumentsAndHedgesLiabilitiesNoncurrent" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_DerivativeOutstandingOnDerivative" xlink:href="ocln-20230930.xsd#ocln_DerivativeOutstandingOnDerivative"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="ocln_DerivativeOutstandingOnDerivative" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CapitalUnitsTotalCostToInvestors" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CapitalUnitsTotalCostToInvestors"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_CapitalUnitsTotalCostToInvestors" order="7" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/CapitalStockDetails">
<loc xlink:type="locator" xlink:label="ocln_CapitalStockLineItems" xlink:href="ocln-20230930.xsd#ocln_CapitalStockLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_CapitalStockDetailsTable" xlink:href="ocln-20230930.xsd#ocln_CapitalStockDetailsTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_CapitalStockDetailsTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_CapitalStockDetailsTable" xlink:to="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:to="us-gaap_RelatedPartyDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:to="us-gaap_RelatedPartyDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_CapitalStockDetailsTable" xlink:to="us-gaap_RelatedPartyTransactionAxis" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RelatedPartyTransactionAxis" xlink:to="us-gaap_RelatedPartyTransactionDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RelatedPartyTransactionAxis" xlink:to="us-gaap_RelatedPartyTransactionDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_TitleOfIndividualAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_TitleOfIndividualAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_CapitalStockDetailsTable" xlink:to="srt_TitleOfIndividualAxis" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_TitleOfIndividualAxis" xlink:to="srt_TitleOfIndividualWithRelationshipToEntityDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain_0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_TitleOfIndividualAxis" xlink:to="srt_TitleOfIndividualWithRelationshipToEntityDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementClassOfStockAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_CapitalStockDetailsTable" xlink:to="us-gaap_StatementClassOfStockAxis" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_ConsolidatedEntitiesAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_CapitalStockDetailsTable" xlink:to="srt_ConsolidatedEntitiesAxis" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_ConsolidatedEntitiesDomain" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_ConsolidatedEntitiesDomain_0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_CapitalStockDetailsTable" xlink:to="srt_RangeAxis" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeMember_0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementEquityComponentsAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_CapitalStockDetailsTable" xlink:to="us-gaap_StatementEquityComponentsAxis" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_CapitalStockDetailsTable" xlink:to="us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherPostretirementBenefitsIndividualContractsTypeOfDeferredCompensationDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherPostretirementBenefitsIndividualContractsTypeOfDeferredCompensationDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis" xlink:to="us-gaap_OtherPostretirementBenefitsIndividualContractsTypeOfDeferredCompensationDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherPostretirementBenefitsIndividualContractsTypeOfDeferredCompensationDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherPostretirementBenefitsIndividualContractsTypeOfDeferredCompensationDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis" xlink:to="us-gaap_OtherPostretirementBenefitsIndividualContractsTypeOfDeferredCompensationDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesIPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesIPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="ocln_SeriesIPreferredStockMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_CommonStockMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_PreferredStockMember" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WaterOnDemandIncWODIPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_WaterOnDemandIncWODIPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="ocln_WaterOnDemandIncWODIPreferredStockMember" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WODIMember" xlink:href="ocln-20230930.xsd#ocln_WODIMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="ocln_WODIMember" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_OriginClearIncCommonStockMember" xlink:href="ocln-20230930.xsd#ocln_OriginClearIncCommonStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="ocln_OriginClearIncCommonStockMember" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_OriginClearPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_OriginClearPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ConsolidatedEntitiesDomain" xlink:to="ocln_OriginClearPreferredStockMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SeriesCPreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesCPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesCPreferredStockMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesD1PreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesD1PreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesD1PreferredStockMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SeriesFPreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesFPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesFPreferredStockMember" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SeriesGPreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesGPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesGPreferredStockMember" order="3" xbrldt:closed="true"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesIPreferredStockMember" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesJPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesJPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesJPreferredStockMember" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesKPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesKPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesKPreferredStockMember" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesLreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesLreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesLreferredStockMember" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesMPreferredStockThreeMember" xlink:href="ocln-20230930.xsd#ocln_SeriesMPreferredStockThreeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesMPreferredStockThreeMember" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesOReferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesOReferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesOReferredStockMember" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesPPreferredStocksMember" xlink:href="ocln-20230930.xsd#ocln_SeriesPPreferredStocksMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesPPreferredStocksMember" order="10" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesQPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesQPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesQPreferredStockMember" order="11" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesYPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesYPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesYPreferredStockMember" order="12" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesZPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesZPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesZPreferredStockMember" order="13" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesRPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesRPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesRPreferredStockMember" order="14" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesSPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesSPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesSPreferredStockMember" order="15" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesUPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesUPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesUPreferredStockMember" order="16" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesWPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesWPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesWPreferredStockMember" order="17" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesXPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesXPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesXPreferredStockMember" order="18" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesVPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesVPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesVPreferredStockMember" order="19" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesTPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesTPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesTPreferredStockMember" order="20" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SeriesAPreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesAPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesAPreferredStockMember" order="21" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SeriesBPreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesBPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesBPreferredStockMember" order="22" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesAAndSeriesBPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesAAndSeriesBPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesAAndSeriesBPreferredStockMember" order="23" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PreferredStockIncentiveCompensationMember" xlink:href="ocln-20230930.xsd#ocln_PreferredStockIncentiveCompensationMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherPostretirementBenefitsIndividualContractsTypeOfDeferredCompensationDomain" xlink:to="ocln_PreferredStockIncentiveCompensationMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_MaximumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_MinimumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_MrEckelberryMember" xlink:href="ocln-20230930.xsd#ocln_MrEckelberryMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyDomain" xlink:to="ocln_MrEckelberryMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_OriginClearIncPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_OriginClearIncPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyDomain" xlink:to="ocln_OriginClearIncPreferredStockMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_BoardOfDirectorsChairmanMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_BoardOfDirectorsChairmanMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="srt_BoardOfDirectorsChairmanMember" order="0" xbrldt:closed="true"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_WODIMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_FinancingAgreementMember" xlink:href="ocln-20230930.xsd#ocln_FinancingAgreementMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_FinancingAgreementMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConvertiblePromissoryNotesMember" xlink:href="ocln-20230930.xsd#ocln_ConvertiblePromissoryNotesMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_ConvertiblePromissoryNotesMember" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ServicesMember" xlink:href="ocln-20230930.xsd#ocln_ServicesMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_ServicesMember" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConversionAgreementsMember" xlink:href="ocln-20230930.xsd#ocln_ConversionAgreementsMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_ConversionAgreementsMember" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ProgressiveWaterTreatmentIncMember" xlink:href="ocln-20230930.xsd#ocln_ProgressiveWaterTreatmentIncMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_ProgressiveWaterTreatmentIncMember" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SharesIssued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesIssued"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_SharesIssued" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PreferredStockPerShare" xlink:href="ocln-20230930.xsd#ocln_PreferredStockPerShare"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_PreferredStockPerShare" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PercentageOfVotingShares" xlink:href="ocln-20230930.xsd#ocln_PercentageOfVotingShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_PercentageOfVotingShares" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PurchasePriceOfPreferredStock" xlink:href="ocln-20230930.xsd#ocln_PurchasePriceOfPreferredStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_PurchasePriceOfPreferredStock" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PurchasePriceOfPreferredStockShares" xlink:href="ocln-20230930.xsd#ocln_PurchasePriceOfPreferredStockShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_PurchasePriceOfPreferredStockShares" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PreferredStockShareOutstanding" xlink:href="ocln-20230930.xsd#ocln_PreferredStockShareOutstanding"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_PreferredStockShareOutstanding" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesAuthorized" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesAuthorized"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_PreferredStockSharesAuthorized" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConvertiblePreferredStockPerShare" xlink:href="ocln-20230930.xsd#ocln_ConvertiblePreferredStockPerShare"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_ConvertiblePreferredStockPerShare" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PercentageOfCommonStockOutstanding" xlink:href="ocln-20230930.xsd#ocln_PercentageOfCommonStockOutstanding"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_PercentageOfCommonStockOutstanding" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_IncreasedCommonStockPercentage" xlink:href="ocln-20230930.xsd#ocln_IncreasedCommonStockPercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_IncreasedCommonStockPercentage" order="10" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesIssued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesIssued"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_PreferredStockSharesIssued" order="11" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesOutstanding"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_PreferredStockSharesOutstanding" order="12" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_DesignatedPreferredStockIssued" xlink:href="ocln-20230930.xsd#ocln_DesignatedPreferredStockIssued"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_DesignatedPreferredStockIssued" order="13" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockLiquidationPreference" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockLiquidationPreference"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_PreferredStockLiquidationPreference" order="14" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AnnualRatePercentage" xlink:href="ocln-20230930.xsd#ocln_AnnualRatePercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_AnnualRatePercentage" order="15" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AggregateRedemptionPrice" xlink:href="ocln-20230930.xsd#ocln_AggregateRedemptionPrice"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_AggregateRedemptionPrice" order="16" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockParOrStatedValuePerShare"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_PreferredStockParOrStatedValuePerShare" order="17" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_DividedClosingPrice" xlink:href="ocln-20230930.xsd#ocln_DividedClosingPrice"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_DividedClosingPrice" order="18" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AggregateOfShares" xlink:href="ocln-20230930.xsd#ocln_AggregateOfShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_AggregateOfShares" order="19" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PreferredStockDescription" xlink:href="ocln-20230930.xsd#ocln_PreferredStockDescription"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_PreferredStockDescription" order="20" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SharesOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesOutstanding"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_SharesOutstanding" order="21" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PreferredStockSharesIssuedAndOutstanding" xlink:href="ocln-20230930.xsd#ocln_PreferredStockSharesIssuedAndOutstanding"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_PreferredStockSharesIssuedAndOutstanding" order="22" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockDividendRatePercentage" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockDividendRatePercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_PreferredStockDividendRatePercentage" order="23" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConversionOfPreferredShares" xlink:href="ocln-20230930.xsd#ocln_ConversionOfPreferredShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_ConversionOfPreferredShares" order="24" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion" order="25" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PreferredStatedValue" xlink:href="ocln-20230930.xsd#ocln_PreferredStatedValue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_PreferredStatedValue" order="26" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockLiquidationPreferenceValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockLiquidationPreferenceValue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_PreferredStockLiquidationPreferenceValue" order="27" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_RedemptionPricePerShare" xlink:href="ocln-20230930.xsd#ocln_RedemptionPricePerShare"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_RedemptionPricePerShare" order="28" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_StatedValuePercentage" xlink:href="ocln-20230930.xsd#ocln_StatedValuePercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_StatedValuePercentage" order="29" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DebtConversionConvertedInstrumentRate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtConversionConvertedInstrumentRate"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_DebtConversionConvertedInstrumentRate" order="30" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_OutstandingCommonStockPercentage" xlink:href="ocln-20230930.xsd#ocln_OutstandingCommonStockPercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_OutstandingCommonStockPercentage" order="31" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConversionOfStockSharesIssued" xlink:href="ocln-20230930.xsd#ocln_ConversionOfStockSharesIssued"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_ConversionOfStockSharesIssued" order="32" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockPerShareAmountsOfPreferredDividendsInArrears" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockPerShareAmountsOfPreferredDividendsInArrears"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_PreferredStockPerShareAmountsOfPreferredDividendsInArrears" order="33" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PercentageOfCommonStock" xlink:href="ocln-20230930.xsd#ocln_PercentageOfCommonStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_PercentageOfCommonStock" order="34" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockOutstandingIncreasedPercentage" xlink:href="ocln-20230930.xsd#ocln_CommonStockOutstandingIncreasedPercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_CommonStockOutstandingIncreasedPercentage" order="35" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AggregateSharesIssued" xlink:href="ocln-20230930.xsd#ocln_AggregateSharesIssued"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_AggregateSharesIssued" order="36" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_CommonStockParOrStatedValuePerShare" order="37" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConversionPricePercentage" xlink:href="ocln-20230930.xsd#ocln_ConversionPricePercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_ConversionPricePercentage" order="38" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants" order="39" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueAdjustmentOfWarrants" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAdjustmentOfWarrants"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_FairValueAdjustmentOfWarrants" order="40" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_WarrantExercisePriceIncrease" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WarrantExercisePriceIncrease"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_WarrantExercisePriceIncrease" order="41" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AggregateShare" xlink:href="ocln-20230930.xsd#ocln_AggregateShare"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_AggregateShare" order="42" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_subscriptionAgreementPercentage" xlink:href="ocln-20230930.xsd#ocln_subscriptionAgreementPercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_subscriptionAgreementPercentage" order="43" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_subscriptionAgreement" xlink:href="ocln-20230930.xsd#ocln_subscriptionAgreement"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_subscriptionAgreement" order="44" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_originalPurchasePrice" xlink:href="ocln-20230930.xsd#ocln_originalPurchasePrice"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_originalPurchasePrice" order="45" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OriginationOfLoanToPurchaseCommonStock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OriginationOfLoanToPurchaseCommonStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_OriginationOfLoanToPurchaseCommonStock" order="46" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_DividedPrice" xlink:href="ocln-20230930.xsd#ocln_DividedPrice"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_DividedPrice" order="47" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_OriginalIssuePrice" xlink:href="ocln-20230930.xsd#ocln_OriginalIssuePrice"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_OriginalIssuePrice" order="48" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AnnualNetProfitsPercentage" xlink:href="ocln-20230930.xsd#ocln_AnnualNetProfitsPercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_AnnualNetProfitsPercentage" order="49" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SubsidiarysAnnualNetProfits" xlink:href="ocln-20230930.xsd#ocln_SubsidiarysAnnualNetProfits"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_SubsidiarysAnnualNetProfits" order="50" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_NumberOfAcquireWarrantShares" xlink:href="ocln-20230930.xsd#ocln_NumberOfAcquireWarrantShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_NumberOfAcquireWarrantShares" order="51" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockValue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_PreferredStockValue" order="52" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PreferredStockFairValue" xlink:href="ocln-20230930.xsd#ocln_PreferredStockFairValue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_PreferredStockFairValue" order="53" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" order="54" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonStockSharesOutstandingPercentage" xlink:href="ocln-20230930.xsd#ocln_CommonStockSharesOutstandingPercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_CommonStockSharesOutstandingPercentage" order="55" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_RealPropertyCost" xlink:href="ocln-20230930.xsd#ocln_RealPropertyCost"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_RealPropertyCost" order="56" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PreferredStockPurchasePrice" xlink:href="ocln-20230930.xsd#ocln_PreferredStockPurchasePrice"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_PreferredStockPurchasePrice" order="57" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_NumberOfWarrantsShares" xlink:href="ocln-20230930.xsd#ocln_NumberOfWarrantsShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_NumberOfWarrantsShares" order="58" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AggregateShares" xlink:href="ocln-20230930.xsd#ocln_AggregateShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_AggregateShares" order="59" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AccruedDividends" xlink:href="ocln-20230930.xsd#ocln_AccruedDividends"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_AccruedDividends" order="60" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DebtConversionConvertedInstrumentSharesIssued1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtConversionConvertedInstrumentSharesIssued1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_DebtConversionConvertedInstrumentSharesIssued1" order="61" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_DebtInstrumentConvertibleConversionPrice1" order="62" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockValue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_CommonStockValue" order="63" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SaleOfAggregateShares" xlink:href="ocln-20230930.xsd#ocln_SaleOfAggregateShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_SaleOfAggregateShares" order="64" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AuctionMarketPreferredSecuritiesStockSeriesParValuePerShare" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AuctionMarketPreferredSecuritiesStockSeriesParValuePerShare"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_AuctionMarketPreferredSecuritiesStockSeriesParValuePerShare" order="65" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SaleOfStockPricePerShare" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockPricePerShare"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_SaleOfStockPricePerShare" order="66" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherExpenses" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherExpenses"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_OtherExpenses" order="67" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_CommonSharesIssued" xlink:href="ocln-20230930.xsd#ocln_CommonSharesIssued"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_CommonSharesIssued" order="68" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PaymentsOfFinancingCosts" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsOfFinancingCosts"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_PaymentsOfFinancingCosts" order="69" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentFaceAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentFaceAmount"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_DebtInstrumentFaceAmount" order="70" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentIncreaseAccruedInterest" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentIncreaseAccruedInterest"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_DebtInstrumentIncreaseAccruedInterest" order="71" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConvertibleDebt" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertibleDebt"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_ConvertibleDebt" order="72" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_LongTermDebtFairValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtFairValue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_LongTermDebtFairValue" order="73" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConversionOfCommonShares" xlink:href="ocln-20230930.xsd#ocln_ConversionOfCommonShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_ConversionOfCommonShares" order="74" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockRedeemedOrCalledDuringPeriodShares" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRedeemedOrCalledDuringPeriodShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_StockRedeemedOrCalledDuringPeriodShares" order="75" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SharePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharePrice"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_SharePrice" order="76" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_RedeemedCommonStockValue" xlink:href="ocln-20230930.xsd#ocln_RedeemedCommonStockValue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_RedeemedCommonStockValue" order="77" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SaleOfSecurities" xlink:href="ocln-20230930.xsd#ocln_SaleOfSecurities"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_SaleOfSecurities" order="78" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ProceedsFromSaleOfShares" xlink:href="ocln-20230930.xsd#ocln_ProceedsFromSaleOfShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="ocln_ProceedsFromSaleOfShares" order="79" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConversionOfStockSharesConverted1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConversionOfStockSharesConverted1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_ConversionOfStockSharesConverted1" order="80" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockConversionBasis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockConversionBasis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_PreferredStockConversionBasis" order="81" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockConversionBasis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockConversionBasis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_CommonStockConversionBasis" order="82" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockholdersEquityNoteStockSplit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityNoteStockSplit"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_StockholdersEquityNoteStockSplit" order="83" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesIssued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesIssued"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_CommonStockSharesIssued" order="84" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesOutstanding"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_CommonStockSharesOutstanding" order="85" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesAuthorized" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesAuthorized"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CapitalStockLineItems" xlink:to="us-gaap_CommonStockSharesAuthorized" order="86" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/OptionsandWarrantsDetails">
<loc xlink:type="locator" xlink:label="ocln_OptionsandWarrantsDetailsLineItems" xlink:href="ocln-20230930.xsd#ocln_OptionsandWarrantsDetailsLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_OptionsandWarrantsDetailsTable" xlink:href="ocln-20230930.xsd#ocln_OptionsandWarrantsDetailsTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_OptionsandWarrantsDetailsLineItems" xlink:to="ocln_OptionsandWarrantsDetailsTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_OptionsandWarrantsDetailsTable" xlink:to="us-gaap_RelatedPartyTransactionAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RelatedPartyTransactionAxis" xlink:to="us-gaap_RelatedPartyTransactionDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RelatedPartyTransactionAxis" xlink:to="us-gaap_RelatedPartyTransactionDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_OptionsandWarrantsDetailsTable" xlink:to="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:to="us-gaap_RelatedPartyDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:to="us-gaap_RelatedPartyDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_TitleOfIndividualAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_TitleOfIndividualAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_OptionsandWarrantsDetailsTable" xlink:to="srt_TitleOfIndividualAxis" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_TitleOfIndividualAxis" xlink:to="srt_TitleOfIndividualWithRelationshipToEntityDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain_0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_TitleOfIndividualAxis" xlink:to="srt_TitleOfIndividualWithRelationshipToEntityDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_OptionsandWarrantsDetailsTable" xlink:to="srt_RangeAxis" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeMember_0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SubsidiarySaleOfStockAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_OptionsandWarrantsDetailsTable" xlink:to="us-gaap_SubsidiarySaleOfStockAxis" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SaleOfStockNameOfTransactionDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_SubsidiarySaleOfStockAxis" xlink:to="us-gaap_SaleOfStockNameOfTransactionDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SaleOfStockNameOfTransactionDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_SubsidiarySaleOfStockAxis" xlink:to="us-gaap_SaleOfStockNameOfTransactionDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_MaximumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_MinimumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SaleOfStockNameOfTransactionDomain" xlink:to="us-gaap_CommonStockMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_RestrictedStockGrantAgreementMember" xlink:href="ocln-20230930.xsd#ocln_RestrictedStockGrantAgreementMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyDomain" xlink:to="ocln_RestrictedStockGrantAgreementMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_ChiefExecutiveOfficerMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ChiefExecutiveOfficerMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="srt_ChiefExecutiveOfficerMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_BoardEmployeesAndConsultantsMember" xlink:href="ocln-20230930.xsd#ocln_BoardEmployeesAndConsultantsMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="ocln_BoardEmployeesAndConsultantsMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_EmployeeConsultantsAndRestrictedStockGrantAgreementsMember" xlink:href="ocln-20230930.xsd#ocln_EmployeeConsultantsAndRestrictedStockGrantAgreementsMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_EmployeeConsultantsAndRestrictedStockGrantAgreementsMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesIssued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesIssued"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsLineItems" xlink:to="us-gaap_CommonStockSharesIssued" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_GrossProfit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GrossProfit"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsLineItems" xlink:to="us-gaap_GrossProfit" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OperatingIncomeLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingIncomeLoss"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsLineItems" xlink:to="us-gaap_OperatingIncomeLoss" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AggregateSharesOfCommonStock" xlink:href="ocln-20230930.xsd#ocln_AggregateSharesOfCommonStock"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsLineItems" xlink:to="ocln_AggregateSharesOfCommonStock" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_BoardOfDirectorsAmendmentDescription" xlink:href="ocln-20230930.xsd#ocln_BoardOfDirectorsAmendmentDescription"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsLineItems" xlink:to="ocln_BoardOfDirectorsAmendmentDescription" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AggregateShareIssued" xlink:href="ocln-20230930.xsd#ocln_AggregateShareIssued"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsLineItems" xlink:to="ocln_AggregateShareIssued" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_IssuedOfPurchaseWarrants" xlink:href="ocln-20230930.xsd#ocln_IssuedOfPurchaseWarrants"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsLineItems" xlink:to="ocln_IssuedOfPurchaseWarrants" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DerivativeLiabilitiesCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilitiesCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsLineItems" xlink:to="us-gaap_DerivativeLiabilitiesCurrent" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_WarrantsAndRightsOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WarrantsAndRightsOutstanding"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_OptionsandWarrantsDetailsLineItems" xlink:to="us-gaap_WarrantsAndRightsOutstanding" order="10" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/ConvertiblePromissoryNotesDetails">
<loc xlink:type="locator" xlink:label="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:href="ocln-20230930.xsd#ocln_ConvertiblePromissoryNotesDetailsLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_ConvertiblePromissoryNotesDetailsTable" xlink:href="ocln-20230930.xsd#ocln_ConvertiblePromissoryNotesDetailsTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="ocln_ConvertiblePromissoryNotesDetailsTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_ConvertiblePromissoryNotesDetailsTable" xlink:to="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:to="us-gaap_RelatedPartyDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:to="us-gaap_RelatedPartyDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShortTermDebtTypeAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtTypeAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_ConvertiblePromissoryNotesDetailsTable" xlink:to="us-gaap_ShortTermDebtTypeAxis" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShortTermDebtTypeDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtTypeDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ShortTermDebtTypeAxis" xlink:to="us-gaap_ShortTermDebtTypeDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShortTermDebtTypeDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtTypeDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ShortTermDebtTypeAxis" xlink:to="us-gaap_ShortTermDebtTypeDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementClassOfStockAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_ConvertiblePromissoryNotesDetailsTable" xlink:to="us-gaap_StatementClassOfStockAxis" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ExtinguishmentOfDebtAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ExtinguishmentOfDebtAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_ConvertiblePromissoryNotesDetailsTable" xlink:to="us-gaap_ExtinguishmentOfDebtAxis" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ExtinguishmentOfDebtTypeDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ExtinguishmentOfDebtTypeDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ExtinguishmentOfDebtAxis" xlink:to="us-gaap_ExtinguishmentOfDebtTypeDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ExtinguishmentOfDebtTypeDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ExtinguishmentOfDebtTypeDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ExtinguishmentOfDebtAxis" xlink:to="us-gaap_ExtinguishmentOfDebtTypeDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AwardDateAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardDateAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_ConvertiblePromissoryNotesDetailsTable" xlink:to="us-gaap_AwardDateAxis" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AwardDateDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardDateDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardDateAxis" xlink:to="us-gaap_AwardDateDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AwardDateDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardDateDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AwardDateAxis" xlink:to="us-gaap_AwardDateDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_ConvertiblePromissoryNotesDetailsTable" xlink:to="srt_RangeAxis" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeMember_0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementEquityComponentsAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_ConvertiblePromissoryNotesDetailsTable" xlink:to="us-gaap_StatementEquityComponentsAxis" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_CommonStockMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_OriginalIssueDiscountNotesMember" xlink:href="ocln-20230930.xsd#ocln_OriginalIssueDiscountNotesMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShortTermDebtTypeDomain" xlink:to="ocln_OriginalIssueDiscountNotesMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConvertibleDebtMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertibleDebtMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShortTermDebtTypeDomain" xlink:to="us-gaap_ConvertibleDebtMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConvertiblePromissoryNotesMember" xlink:href="ocln-20230930.xsd#ocln_ConvertiblePromissoryNotesMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShortTermDebtTypeDomain" xlink:to="ocln_ConvertiblePromissoryNotesMember" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesXPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesXPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesXPreferredStockMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesRPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesRPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesRPreferredStockMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShortTermDebtMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ExtinguishmentOfDebtTypeDomain" xlink:to="us-gaap_ShortTermDebtMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_LongTermDebtMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ExtinguishmentOfDebtTypeDomain" xlink:to="us-gaap_LongTermDebtMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_LongTermNotesTwoThousandFifteenMember" xlink:href="ocln-20230930.xsd#ocln_LongTermNotesTwoThousandFifteenMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AwardDateDomain" xlink:to="ocln_LongTermNotesTwoThousandFifteenMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConvertiblePromissoryNotes2015NotesMember" xlink:href="ocln-20230930.xsd#ocln_ConvertiblePromissoryNotes2015NotesMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AwardDateDomain" xlink:to="ocln_ConvertiblePromissoryNotes2015NotesMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_DecemberTwoZeroOneFiveNoteMember" xlink:href="ocln-20230930.xsd#ocln_DecemberTwoZeroOneFiveNoteMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AwardDateDomain" xlink:to="ocln_DecemberTwoZeroOneFiveNoteMember" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeptemberTwoZeroOneSixNoteMember" xlink:href="ocln-20230930.xsd#ocln_SeptemberTwoZeroOneSixNoteMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AwardDateDomain" xlink:to="ocln_SeptemberTwoZeroOneSixNoteMember" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_NovemberTwentyNoteMember" xlink:href="ocln-20230930.xsd#ocln_NovemberTwentyNoteMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AwardDateDomain" xlink:to="ocln_NovemberTwentyNoteMember" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_JanuaryTwentyOneNoteMember" xlink:href="ocln-20230930.xsd#ocln_JanuaryTwentyOneNoteMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AwardDateDomain" xlink:to="ocln_JanuaryTwentyOneNoteMember" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_MinimumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_MaximumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_OriginClearIncTechnologyMember" xlink:href="ocln-20230930.xsd#ocln_OriginClearIncTechnologyMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyDomain" xlink:to="ocln_OriginClearIncTechnologyMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateStatedPercentage" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConversionOfStockAmountConverted1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConversionOfStockAmountConverted1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_ConversionOfStockAmountConverted1" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SharesIssued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesIssued"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_SharesIssued" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PrincipalAmount" xlink:href="ocln-20230930.xsd#ocln_PrincipalAmount"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="ocln_PrincipalAmount" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DepositLiabilitiesAccruedInterest" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DepositLiabilitiesAccruedInterest"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_DepositLiabilitiesAccruedInterest" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueOptionAggregateDifferencesLoansAndLongTermReceivables" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueOptionAggregateDifferencesLoansAndLongTermReceivables"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_FairValueOptionAggregateDifferencesLoansAndLongTermReceivables" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AggregateRemainingAmount" xlink:href="ocln-20230930.xsd#ocln_AggregateRemainingAmount"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="ocln_AggregateRemainingAmount" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentMaturityDate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentMaturityDate"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_DebtInstrumentMaturityDate" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockConvertibleConversionPriceDecrease" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockConvertibleConversionPriceDecrease"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_CommonStockConvertibleConversionPriceDecrease" order="10" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ShortTermRemainingBalance" xlink:href="ocln-20230930.xsd#ocln_ShortTermRemainingBalance"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="ocln_ShortTermRemainingBalance" order="11" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AccountsPayableTradeCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsPayableTradeCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_AccountsPayableTradeCurrent" order="12" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PercentageOfAverageOfThreeLowestClosingPrices" xlink:href="ocln-20230930.xsd#ocln_PercentageOfAverageOfThreeLowestClosingPrices"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="ocln_PercentageOfAverageOfThreeLowestClosingPrices" order="13" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AggregateAmount" xlink:href="ocln-20230930.xsd#ocln_AggregateAmount"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="ocln_AggregateAmount" order="14" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConversionPricePerShareOfDebtDescriptions" xlink:href="ocln-20230930.xsd#ocln_ConversionPricePerShareOfDebtDescriptions"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="ocln_ConversionPricePerShareOfDebtDescriptions" order="15" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_InvestorAmount" xlink:href="ocln-20230930.xsd#ocln_InvestorAmount"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="ocln_InvestorAmount" order="16" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ReservedShares" xlink:href="ocln-20230930.xsd#ocln_ReservedShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="ocln_ReservedShares" order="17" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConvertibleDebt" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertibleDebt"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_ConvertibleDebt" order="18" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromUnsecuredNotesPayable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromUnsecuredNotesPayable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_ProceedsFromUnsecuredNotesPayable" order="19" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PenaltyPerDay" xlink:href="ocln-20230930.xsd#ocln_PenaltyPerDay"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="ocln_PenaltyPerDay" order="20" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_InterestExpenseDebtExcludingAmortization" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpenseDebtExcludingAmortization"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_InterestExpenseDebtExcludingAmortization" order="21" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DebtDefaultShorttermDebtAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtDefaultShorttermDebtAmount"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_DebtDefaultShorttermDebtAmount" order="22" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DerivativeLiabilitiesNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilitiesNoncurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_DerivativeLiabilitiesNoncurrent" order="23" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromSecuredNotesPayable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromSecuredNotesPayable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_ProceedsFromSecuredNotesPayable" order="24" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_InvestorsInterestPercentage" xlink:href="ocln-20230930.xsd#ocln_InvestorsInterestPercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="ocln_InvestorsInterestPercentage" order="25" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SupplementalDeferredPurchasePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SupplementalDeferredPurchasePrice"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_SupplementalDeferredPurchasePrice" order="26" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherAdditionalCapital" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAdditionalCapital"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_OtherAdditionalCapital" order="27" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredUnitsOfferingCosts" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredUnitsOfferingCosts"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_PreferredUnitsOfferingCosts" order="28" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AggregateShare" xlink:href="ocln-20230930.xsd#ocln_AggregateShare"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="ocln_AggregateShare" order="29" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SharePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharePrice"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="us-gaap_SharePrice" order="30" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConvertiblePromissoryNote" xlink:href="ocln-20230930.xsd#ocln_ConvertiblePromissoryNote"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_ConvertiblePromissoryNotesDetailsLineItems" xlink:to="ocln_ConvertiblePromissoryNote" order="31" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/RevenuefromContractswithCustomersDetails">
<loc xlink:type="locator" xlink:label="us-gaap_RevenueFromContractWithCustomerAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerAssetNetCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerAssetNetCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RevenueFromContractWithCustomerAbstract" xlink:to="us-gaap_ContractWithCustomerAssetNetCurrent" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherLiabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLiabilities"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RevenueFromContractWithCustomerAbstract" xlink:to="us-gaap_OtherLiabilities" order="1" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/FinancialAssetsDetails">
<loc xlink:type="locator" xlink:label="ocln_FinancialAssetsDetailsLineItems" xlink:href="ocln-20230930.xsd#ocln_FinancialAssetsDetailsLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_FinancialAssetsDetailsTable" xlink:href="ocln-20230930.xsd#ocln_FinancialAssetsDetailsTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_FinancialAssetsDetailsLineItems" xlink:to="ocln_FinancialAssetsDetailsTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_FinancialAssetsDetailsTable" xlink:to="us-gaap_RelatedPartyTransactionAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RelatedPartyTransactionAxis" xlink:to="us-gaap_RelatedPartyTransactionDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RelatedPartyTransactionAxis" xlink:to="us-gaap_RelatedPartyTransactionDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementClassOfStockAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_FinancialAssetsDetailsTable" xlink:to="us-gaap_StatementClassOfStockAxis" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementEquityComponentsAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_FinancialAssetsDetailsTable" xlink:to="us-gaap_StatementEquityComponentsAxis" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_CommonStockMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SeriesCPreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesCPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesCPreferredStockMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_OriginClearIncTechnologyMember" xlink:href="ocln-20230930.xsd#ocln_OriginClearIncTechnologyMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_OriginClearIncTechnologyMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_InterestAndFeeIncomeLoansAndLeases" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestAndFeeIncomeLoansAndLeases"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_FinancialAssetsDetailsLineItems" xlink:to="us-gaap_InterestAndFeeIncomeLoansAndLeases" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AggregatePrincipalAmount" xlink:href="ocln-20230930.xsd#ocln_AggregatePrincipalAmount"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_FinancialAssetsDetailsLineItems" xlink:to="ocln_AggregatePrincipalAmount" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConversionOfStockShareConverted" xlink:href="ocln-20230930.xsd#ocln_ConversionOfStockShareConverted"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_FinancialAssetsDetailsLineItems" xlink:to="ocln_ConversionOfStockShareConverted" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireTradingSecuritiesHeldforinvestment" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireTradingSecuritiesHeldforinvestment"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_FinancialAssetsDetailsLineItems" xlink:to="us-gaap_PaymentsToAcquireTradingSecuritiesHeldforinvestment" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DebtSecuritiesUnrealizedGainLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesUnrealizedGainLoss"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_FinancialAssetsDetailsLineItems" xlink:to="us-gaap_DebtSecuritiesUnrealizedGainLoss" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConvertiblePreferredStocks" xlink:href="ocln-20230930.xsd#ocln_ConvertiblePreferredStocks"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_FinancialAssetsDetailsLineItems" xlink:to="ocln_ConvertiblePreferredStocks" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_FairValueMarketPricePerShares" xlink:href="ocln-20230930.xsd#ocln_FairValueMarketPricePerShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_FinancialAssetsDetailsLineItems" xlink:to="ocln_FairValueMarketPricePerShares" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SharePriceAmount" xlink:href="ocln-20230930.xsd#ocln_SharePriceAmount"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_FinancialAssetsDetailsLineItems" xlink:to="ocln_SharePriceAmount" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PreferredSharesFairValue" xlink:href="ocln-20230930.xsd#ocln_PreferredSharesFairValue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_FinancialAssetsDetailsLineItems" xlink:to="ocln_PreferredSharesFairValue" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueOptionChangesInFairValueGainLoss1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueOptionChangesInFairValueGainLoss1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_FinancialAssetsDetailsLineItems" xlink:to="us-gaap_FairValueOptionChangesInFairValueGainLoss1" order="10" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/LoansPayableDetails">
<loc xlink:type="locator" xlink:label="ocln_LoansPayableDisclosureAbstract" xlink:href="ocln-20230930.xsd#ocln_LoansPayableDisclosureAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_AdditionsToOtherAssetsAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionsToOtherAssetsAmount"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_LoansPayableDisclosureAbstract" xlink:to="us-gaap_AdditionsToOtherAssetsAmount" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_LeaseCost" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LeaseCost"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_LoansPayableDisclosureAbstract" xlink:to="us-gaap_LeaseCost" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_NotesAndLoansPayable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NotesAndLoansPayable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_LoansPayableDisclosureAbstract" xlink:to="us-gaap_NotesAndLoansPayable" order="2" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/WaterondemandincDetails">
<loc xlink:type="locator" xlink:label="ocln_WaterondemandincDetailsLineItems" xlink:href="ocln-20230930.xsd#ocln_WaterondemandincDetailsLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_WaterondemandincDetailsTable" xlink:href="ocln-20230930.xsd#ocln_WaterondemandincDetailsTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_WaterondemandincDetailsTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_WaterondemandincDetailsTable" xlink:to="us-gaap_RelatedPartyTransactionAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RelatedPartyTransactionAxis" xlink:to="us-gaap_RelatedPartyTransactionDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RelatedPartyTransactionAxis" xlink:to="us-gaap_RelatedPartyTransactionDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementClassOfStockAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_WaterondemandincDetailsTable" xlink:to="us-gaap_StatementClassOfStockAxis" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AssetAcquisitionAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetAcquisitionAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_WaterondemandincDetailsTable" xlink:to="us-gaap_AssetAcquisitionAxis" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AssetAcquisitionDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetAcquisitionDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AssetAcquisitionAxis" xlink:to="us-gaap_AssetAcquisitionDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AssetAcquisitionDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetAcquisitionDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AssetAcquisitionAxis" xlink:to="us-gaap_AssetAcquisitionDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_WaterondemandincDetailsTable" xlink:to="us-gaap_DebtInstrumentAxis" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentNameDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentNameDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_VestingAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_WaterondemandincDetailsTable" xlink:to="us-gaap_VestingAxis" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_VestingDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_VestingAxis" xlink:to="us-gaap_VestingDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_VestingDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_VestingAxis" xlink:to="us-gaap_VestingDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementEquityComponentsAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_WaterondemandincDetailsTable" xlink:to="us-gaap_StatementEquityComponentsAxis" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_OwnershipAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_WaterondemandincDetailsTable" xlink:to="srt_OwnershipAxis" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_OwnershipDomain" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_OwnershipAxis" xlink:to="srt_OwnershipDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_OwnershipDomain_0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_OwnershipAxis" xlink:to="srt_OwnershipDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WODMember" xlink:href="ocln-20230930.xsd#ocln_WODMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetAcquisitionDomain" xlink:to="ocln_WODMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_CommonStockMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonClassBMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonClassBMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_CommonClassBMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SeriesAPreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesAPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesAPreferredStockMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SeriesBPreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesBPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesBPreferredStockMember" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationAwardTrancheOneMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_VestingDomain" xlink:to="us-gaap_ShareBasedCompensationAwardTrancheOneMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationAwardTrancheTwoMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationAwardTrancheTwoMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_VestingDomain" xlink:to="us-gaap_ShareBasedCompensationAwardTrancheTwoMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SPACMember" xlink:href="ocln-20230930.xsd#ocln_SPACMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="ocln_SPACMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_RestrictedStockGrantAgreementsMember" xlink:href="ocln-20230930.xsd#ocln_RestrictedStockGrantAgreementsMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="ocln_RestrictedStockGrantAgreementsMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SponsorMember" xlink:href="ocln-20230930.xsd#ocln_SponsorMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_SponsorMember" order="0" xbrldt:closed="true"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_SPACMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WODIMember" xlink:href="ocln-20230930.xsd#ocln_WODIMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_WODIMember" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ModularWaterSystemsMember" xlink:href="ocln-20230930.xsd#ocln_ModularWaterSystemsMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_ModularWaterSystemsMember" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WODIAndMWSMember" xlink:href="ocln-20230930.xsd#ocln_WODIAndMWSMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_WODIAndMWSMember" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PWTMember" xlink:href="ocln-20230930.xsd#ocln_PWTMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_PWTMember" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PWTOneMember" xlink:href="ocln-20230930.xsd#ocln_PWTOneMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_PWTOneMember" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ProgressiveWaterTreatmentIncMember" xlink:href="ocln-20230930.xsd#ocln_ProgressiveWaterTreatmentIncMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_ProgressiveWaterTreatmentIncMember" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_OriginClearIncMember" xlink:href="ocln-20230930.xsd#ocln_OriginClearIncMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_OriginClearIncMember" order="8" xbrldt:closed="true"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_RestrictedStockGrantAgreementsMember" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WODIBoardMember" xlink:href="ocln-20230930.xsd#ocln_WODIBoardMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="ocln_WODIBoardMember" order="10" xbrldt:closed="true"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_OwnershipDomain" xlink:to="ocln_SponsorMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WaterOnDemandIncDescription" xlink:href="ocln-20230930.xsd#ocln_WaterOnDemandIncDescription"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_WaterOnDemandIncDescription" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherInvestments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherInvestments"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_OtherInvestments" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_MembershipInterestPercentage" xlink:href="ocln-20230930.xsd#ocln_MembershipInterestPercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_MembershipInterestPercentage" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SponsorOwnsShares" xlink:href="ocln-20230930.xsd#ocln_SponsorOwnsShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_SponsorOwnsShares" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesIssued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesIssued"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_CommonStockSharesIssued" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesOutstanding"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_CommonStockSharesOutstanding" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PaidTotalAmount" xlink:href="ocln-20230930.xsd#ocln_PaidTotalAmount"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_PaidTotalAmount" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_MembershipInterestAmount" xlink:href="ocln-20230930.xsd#ocln_MembershipInterestAmount"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_MembershipInterestAmount" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CompensatingBalanceAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CompensatingBalanceAmount"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_CompensatingBalanceAmount" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInNotesPayableRelatedPartiesCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInNotesPayableRelatedPartiesCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_IncreaseDecreaseInNotesPayableRelatedPartiesCurrent" order="10" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PurchasePrice" xlink:href="ocln-20230930.xsd#ocln_PurchasePrice"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_PurchasePrice" order="11" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentInterestRateIncreaseDecrease" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateIncreaseDecrease"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateIncreaseDecrease" order="12" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_Deposits" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Deposits"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_Deposits" order="13" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SaleOfStockPricePerShare" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockPricePerShare"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_SaleOfStockPricePerShare" order="14" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesOther" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesOther"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesOther" order="15" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SpecialMeetingTotalNumberOfPercentage" xlink:href="ocln-20230930.xsd#ocln_SpecialMeetingTotalNumberOfPercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_SpecialMeetingTotalNumberOfPercentage" order="16" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SufficientVotesPercentage" xlink:href="ocln-20230930.xsd#ocln_SufficientVotesPercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_SufficientVotesPercentage" order="17" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_OtherAssetsExchangeShares" xlink:href="ocln-20230930.xsd#ocln_OtherAssetsExchangeShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_OtherAssetsExchangeShares" order="18" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsEquityMethodInvestments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsEquityMethodInvestments"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_DeferredTaxAssetsEquityMethodInvestments" order="19" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CashHeldInForeignCurrency" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashHeldInForeignCurrency"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_CashHeldInForeignCurrency" order="20" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_VariableInterestEntityOwnershipPercentage" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableInterestEntityOwnershipPercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_VariableInterestEntityOwnershipPercentage" order="21" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ShareholdersPercentage" xlink:href="ocln-20230930.xsd#ocln_ShareholdersPercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_ShareholdersPercentage" order="22" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AssetAcquisitionPriceOfAcquisitionExpected" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetAcquisitionPriceOfAcquisitionExpected"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_AssetAcquisitionPriceOfAcquisitionExpected" order="23" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_EquityCombinedPercentage" xlink:href="ocln-20230930.xsd#ocln_EquityCombinedPercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_EquityCombinedPercentage" order="24" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_TotalShares" xlink:href="ocln-20230930.xsd#ocln_TotalShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_TotalShares" order="25" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_IssuedAndOutstandingPercentage" xlink:href="ocln-20230930.xsd#ocln_IssuedAndOutstandingPercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_IssuedAndOutstandingPercentage" order="26" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AdditionalTerm" xlink:href="ocln-20230930.xsd#ocln_AdditionalTerm"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_AdditionalTerm" order="27" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AggregateAmountsOfSPAC" xlink:href="ocln-20230930.xsd#ocln_AggregateAmountsOfSPAC"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_AggregateAmountsOfSPAC" order="28" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromUnsecuredNotesPayable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromUnsecuredNotesPayable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_ProceedsFromUnsecuredNotesPayable" order="29" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateEffectivePercentage" order="30" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherNotesPayable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNotesPayable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_OtherNotesPayable" order="31" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherAssetsCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_OtherAssetsCurrent" order="32" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ExchangeShares" xlink:href="ocln-20230930.xsd#ocln_ExchangeShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_ExchangeShares" order="33" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_ConsiderationShares" xlink:href="ocln-20230930.xsd#ocln_ConsiderationShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_ConsiderationShares" order="34" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" order="35" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DeferredRevenue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredRevenue"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_DeferredRevenue" order="36" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SharePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharePrice"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_SharePrice" order="37" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction" order="38" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SharesIssued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesIssued"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_SharesIssued" order="39" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RestrictedInvestmentsPercentOfNetAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedInvestmentsPercentOfNetAssets"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_RestrictedInvestmentsPercentOfNetAssets" order="40" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage" order="41" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum" order="42" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="us-gaap_DebtInstrumentConvertibleConversionPrice1" order="43" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_IssuanceOfShares" xlink:href="ocln-20230930.xsd#ocln_IssuanceOfShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_WaterondemandincDetailsLineItems" xlink:to="ocln_IssuanceOfShares" order="44" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/LineofCreditDetails">
<loc xlink:type="locator" xlink:label="us-gaap_DebtDisclosureAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtDisclosureAbstract"/>
<loc xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityIncreaseDecreaseForPeriodNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityIncreaseDecreaseForPeriodNet"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtDisclosureAbstract" xlink:to="us-gaap_LineOfCreditFacilityIncreaseDecreaseForPeriodNet" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityInterestRateDuringPeriod" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityInterestRateDuringPeriod"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtDisclosureAbstract" xlink:to="us-gaap_LineOfCreditFacilityInterestRateDuringPeriod" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PrincipalInvestmentGainsLosses" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrincipalInvestmentGainsLosses"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtDisclosureAbstract" xlink:to="us-gaap_PrincipalInvestmentGainsLosses" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_InvestmentSoldNotYetPurchasedBalancePrincipalAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InvestmentSoldNotYetPurchasedBalancePrincipalAmount"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtDisclosureAbstract" xlink:to="us-gaap_InvestmentSoldNotYetPurchasedBalancePrincipalAmount" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtDisclosureAbstract" xlink:to="us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity" order="4" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/AssetsHeldforSaleDetails">
<loc xlink:type="locator" xlink:label="ocln_AssetsHeldforSaleDetailsLineItems" xlink:href="ocln-20230930.xsd#ocln_AssetsHeldforSaleDetailsLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_AssetsHeldforSaleDetailsTable" xlink:href="ocln-20230930.xsd#ocln_AssetsHeldforSaleDetailsTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="ocln_AssetsHeldforSaleDetailsTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementClassOfStockAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_AssetsHeldforSaleDetailsTable" xlink:to="us-gaap_StatementClassOfStockAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_AssetsHeldforSaleDetailsTable" xlink:to="srt_RangeAxis" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_RangeMember_0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueByAssetClassAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByAssetClassAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_AssetsHeldforSaleDetailsTable" xlink:to="us-gaap_FairValueByAssetClassAxis" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByAssetClassAxis" xlink:to="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_FairValueByAssetClassAxis" xlink:to="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_MaximumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="srt_MinimumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:to="us-gaap_PropertyPlantAndEquipmentMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesTPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesTPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesTPreferredStockMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PreferredStockConvertibleSharesIssuable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockConvertibleSharesIssuable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="us-gaap_PreferredStockConvertibleSharesIssuable" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_NumberOfWarrantsShares" xlink:href="ocln-20230930.xsd#ocln_NumberOfWarrantsShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="ocln_NumberOfWarrantsShares" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_CommonStockDividendsPerShareDeclared" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="us-gaap_CommonStockDividendsPerShareDeclared" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ServicingAssetAtFairValueAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ServicingAssetAtFairValueAmount"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="us-gaap_ServicingAssetAtFairValueAmount" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_PrivateNeighborhoodDevelopment" xlink:href="ocln-20230930.xsd#ocln_PrivateNeighborhoodDevelopment"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="ocln_PrivateNeighborhoodDevelopment" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherLongTermDebt" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLongTermDebt"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="us-gaap_OtherLongTermDebt" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerAssetSale" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerAssetSale"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="us-gaap_ContractWithCustomerAssetSale" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AssetImpairmentCharges" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetImpairmentCharges"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="us-gaap_AssetImpairmentCharges" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DeferredOfferingCosts" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredOfferingCosts"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="us-gaap_DeferredOfferingCosts" order="10" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_DeferredGainOnSaleOfProperty" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredGainOnSaleOfProperty"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="us-gaap_DeferredGainOnSaleOfProperty" order="11" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_InitialPayment" xlink:href="ocln-20230930.xsd#ocln_InitialPayment"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="ocln_InitialPayment" order="12" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_RemainingInitialPayment" xlink:href="ocln-20230930.xsd#ocln_RemainingInitialPayment"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="ocln_RemainingInitialPayment" order="13" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ReplacementReserveEscrow" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReplacementReserveEscrow"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="us-gaap_ReplacementReserveEscrow" order="14" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromCommissionsReceived" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromCommissionsReceived"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="us-gaap_ProceedsFromCommissionsReceived" order="15" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_PaymentsForFees" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsForFees"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="us-gaap_PaymentsForFees" order="16" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AccountsReceivablePurchase" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsReceivablePurchase"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="us-gaap_AccountsReceivablePurchase" order="17" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AdditionalPaymentsTotal" xlink:href="ocln-20230930.xsd#ocln_AdditionalPaymentsTotal"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="ocln_AdditionalPaymentsTotal" order="18" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherReceivables" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherReceivables"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_AssetsHeldforSaleDetailsLineItems" xlink:to="us-gaap_OtherReceivables" order="19" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/EmployeeRetentionTaxCreditDetails">
<loc xlink:type="locator" xlink:label="ocln_EmployeeRetentionTaxCreditDetailsLineItems" xlink:href="ocln-20230930.xsd#ocln_EmployeeRetentionTaxCreditDetailsLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_EmployeeRetentionTaxCreditDetailsTable" xlink:href="ocln-20230930.xsd#ocln_EmployeeRetentionTaxCreditDetailsTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_EmployeeRetentionTaxCreditDetailsLineItems" xlink:to="ocln_EmployeeRetentionTaxCreditDetailsTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherIncome" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherIncome"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_EmployeeRetentionTaxCreditDetailsLineItems" xlink:to="us-gaap_OtherIncome" order="1" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/CommitmentsandContingenciesDetails">
<loc xlink:type="locator" xlink:label="ocln_CommitmentsandContingenciesDetailsLineItems" xlink:href="ocln-20230930.xsd#ocln_CommitmentsandContingenciesDetailsLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_CommitmentsandContingenciesDetailsTable" xlink:href="ocln-20230930.xsd#ocln_CommitmentsandContingenciesDetailsTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_CommitmentsandContingenciesDetailsLineItems" xlink:to="ocln_CommitmentsandContingenciesDetailsTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherCommitmentsAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCommitmentsAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_CommitmentsandContingenciesDetailsTable" xlink:to="us-gaap_OtherCommitmentsAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherCommitmentsDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCommitmentsDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_OtherCommitmentsAxis" xlink:to="us-gaap_OtherCommitmentsDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_OtherCommitmentsDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCommitmentsDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_OtherCommitmentsAxis" xlink:to="us-gaap_OtherCommitmentsDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_MckinneyMember" xlink:href="ocln-20230930.xsd#ocln_MckinneyMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherCommitmentsDomain" xlink:to="ocln_MckinneyMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_AreaOfLand" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AreaOfLand"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CommitmentsandContingenciesDetailsLineItems" xlink:to="us-gaap_AreaOfLand" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_RentalProperties" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RentalProperties"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CommitmentsandContingenciesDetailsLineItems" xlink:to="us-gaap_RentalProperties" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_WarrantyReserveCurrent" xlink:href="ocln-20230930.xsd#ocln_WarrantyReserveCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_CommitmentsandContingenciesDetailsLineItems" xlink:to="ocln_WarrantyReserveCurrent" order="3" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/SubsequentEventsDetails">
<loc xlink:type="locator" xlink:label="ocln_SubsequentEventsDetailsLineItems" xlink:href="ocln-20230930.xsd#ocln_SubsequentEventsDetailsLineItems"/>
<loc xlink:type="locator" xlink:label="ocln_SubsequentEventsDetailsTable" xlink:href="ocln-20230930.xsd#ocln_SubsequentEventsDetailsTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="ocln_SubsequentEventsDetailsLineItems" xlink:to="ocln_SubsequentEventsDetailsTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_StatementClassOfStockAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_SubsequentEventsDetailsTable" xlink:to="us-gaap_StatementClassOfStockAxis" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SubsequentEventTypeAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="ocln_SubsequentEventsDetailsTable" xlink:to="us-gaap_SubsequentEventTypeAxis" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SubsequentEventTypeDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeDomain" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SubsequentEventTypeDomain_0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeDomain_0" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesRPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesRPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesRPreferredStockMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_SeriesYPreferredStockMember" xlink:href="ocln-20230930.xsd#ocln_SeriesYPreferredStockMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="ocln_SeriesYPreferredStockMember" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_SubsequentEventMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventTypeDomain" xlink:to="us-gaap_SubsequentEventMember" order="0" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConversionOfStockSharesConverted1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConversionOfStockSharesConverted1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_SubsequentEventsDetailsLineItems" xlink:to="us-gaap_ConversionOfStockSharesConverted1" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="us-gaap_ConversionOfStockSharesIssued1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConversionOfStockSharesIssued1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_SubsequentEventsDetailsLineItems" xlink:to="us-gaap_ConversionOfStockSharesIssued1" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AggregateSharesIssued" xlink:href="ocln-20230930.xsd#ocln_AggregateSharesIssued"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_SubsequentEventsDetailsLineItems" xlink:to="ocln_AggregateSharesIssued" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="ocln_AggregateOfShares" xlink:href="ocln-20230930.xsd#ocln_AggregateOfShares"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ocln_SubsequentEventsDetailsLineItems" xlink:to="ocln_AggregateOfShares" order="4" xbrldt:closed="true"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.originclear.com/role/DocumentAndEntityInformation">
<loc xlink:type="locator" xlink:label="dei_DocumentInformationLineItems" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentInformationLineItems"/>
<loc xlink:type="locator" xlink:label="dei_DocumentInformationTable" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentInformationTable"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentInformationTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntityRegistrantName" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityRegistrantName"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityRegistrantName" order="1" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_DocumentType" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentType"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentType" order="2" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_CurrentFiscalYearEndDate" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_CurrentFiscalYearEndDate"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_CurrentFiscalYearEndDate" order="3" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntityCommonStockSharesOutstanding" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityCommonStockSharesOutstanding"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityCommonStockSharesOutstanding" order="4" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_AmendmentFlag" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_AmendmentFlag"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_AmendmentFlag" order="5" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntityCentralIndexKey" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityCentralIndexKey"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityCentralIndexKey" order="6" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntityCurrentReportingStatus" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityCurrentReportingStatus"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityCurrentReportingStatus" order="7" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntityFilerCategory" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityFilerCategory"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityFilerCategory" order="8" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_DocumentPeriodEndDate" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentPeriodEndDate"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentPeriodEndDate" order="9" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_DocumentFiscalYearFocus" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentFiscalYearFocus"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentFiscalYearFocus" order="10" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_DocumentFiscalPeriodFocus" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentFiscalPeriodFocus"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentFiscalPeriodFocus" order="11" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntitySmallBusiness" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntitySmallBusiness"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntitySmallBusiness" order="12" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntityEmergingGrowthCompany" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityEmergingGrowthCompany"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityEmergingGrowthCompany" order="13" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntityShellCompany" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityShellCompany"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityShellCompany" order="14" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_DocumentQuarterlyReport" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentQuarterlyReport"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentQuarterlyReport" order="15" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_DocumentTransitionReport" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentTransitionReport"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentTransitionReport" order="16" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntityFileNumber" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityFileNumber"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityFileNumber" order="17" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntityIncorporationStateCountryCode" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityIncorporationStateCountryCode"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityIncorporationStateCountryCode" order="18" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntityTaxIdentificationNumber" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityTaxIdentificationNumber"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityTaxIdentificationNumber" order="19" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntityAddressAddressLine1" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityAddressAddressLine1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityAddressAddressLine1" order="20" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntityAddressAddressLine2" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityAddressAddressLine2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityAddressAddressLine2" order="21" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntityAddressCityOrTown" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityAddressCityOrTown"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityAddressCityOrTown" order="22" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntityAddressStateOrProvince" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityAddressStateOrProvince"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityAddressStateOrProvince" order="23" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntityAddressPostalZipCode" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityAddressPostalZipCode"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityAddressPostalZipCode" order="24" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_CityAreaCode" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_CityAreaCode"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_CityAreaCode" order="25" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_LocalPhoneNumber" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LocalPhoneNumber"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_LocalPhoneNumber" order="26" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_Security12bTitle" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_Security12bTitle"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_Security12bTitle" order="27" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_SecurityExchangeName" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_SecurityExchangeName"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_SecurityExchangeName" order="28" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_EntityInteractiveDataCurrent" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityInteractiveDataCurrent"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityInteractiveDataCurrent" order="29" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:label="dei_NoTradingSymbolFlag" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_NoTradingSymbolFlag"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_NoTradingSymbolFlag" order="30" xbrldt:closed="true"/>
</definitionLink>
</linkbase>

Top
Filing Submission 0001213900-23-094460   –   Alternative Formats (Word / Rich Text, HTML, Plain Text, et al.)

Copyright © 2024 Fran Finnegan & Company LLC – All Rights Reserved.
AboutPrivacyRedactionsHelp — Mon., May 13, 11:34:07.1pm ET