SEC Info - Alpha Pro Tech Ltd. - ‘10-Q’ for 6/30/22

SEC Info℠

Home

Help

Please Sign In

Alpha Pro Tech Ltd. – ‘10-Q’ for 6/30/22 – ‘EX-101.DEF’

On: Friday, 8/5/22, at 10:53am ET · For: 6/30/22 · Accession #: 1437749-22-19054 · File #: 1-15725

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

 8/05/22  Alpha Pro Tech Ltd.               10-Q        6/30/22   58:3.5M                                   RDG Filings/FA

Quarterly Report — Form 10-Q

Filing Table of Contents

Document/Exhibit                   Description                      Pages   Size 

 1: 10-Q        Quarterly Report                                    HTML    719K 
 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     19K 
11: R1          Document And Entity Information                     HTML     72K 
12: R2          Condensed Consolidated Balance Sheets (Unaudited)   HTML    114K 
13: R3          Condensed Consolidated Balance Sheets               HTML     25K 
                (Unaudited)-parentheticals (Parentheticals)                      
14: R4          Condensed Consolidated Statements of Comprehensive  HTML     92K 
                Income (Unaudited)                                               
15: R5          Condensed Consolidated Statements of Shareholders'  HTML     70K 
                Equity (Unaudited)                                               
16: R6          Condensed Consolidated Statements of Cash Flows     HTML     82K 
                (Unaudited)                                                      
17: R7          Note 1 - The Company                                HTML     24K 
18: R8          Note 2 - Basis of Presentation and Revenue          HTML     25K 
                Recognition Policy                                               
19: R9          Note 3 - Stock-based Compensation                   HTML     35K 
20: R10         Note 4 - Recent Accounting Pronouncements           HTML     30K 
21: R11         Note 5 - Inventories                                HTML     26K 
22: R12         Note 6 - Equity Investment in Unconsolidated        HTML     26K 
                Affiliate                                                        
23: R13         Note 7 - Accrued Liabilities                        HTML     26K 
24: R14         Note 8 - Basic and Diluted Earnings Per Common      HTML     42K 
                Share                                                            
25: R15         Note 9 - Activity of Business Segments              HTML     63K 
26: R16         Note 10 - Financial Information about Geographic    HTML     40K 
                Areas                                                            
27: R17         Note 11 - Related Party Transactions                HTML     21K 
28: R18         Note 12 - Leases                                    HTML     30K 
29: R19         Note 13 - Income Taxes                              HTML     24K 
30: R20         Note 14 - Contingencies                             HTML     23K 
31: R21         Note 15 - Subsequent Events                         HTML     21K 
32: R22         Note 3 - Stock-based Compensation (Tables)          HTML     29K 
33: R23         Note 5 - Inventories (Tables)                       HTML     26K 
34: R24         Note 7 - Accrued Liabilities (Tables)               HTML     24K 
35: R25         Note 8 - Basic and Diluted Earnings Per Common      HTML     41K 
                Share (Tables)                                                   
36: R26         Note 9 - Activity of Business Segments (Tables)     HTML     60K 
37: R27         Note 10 - Financial Information about Geographic    HTML     38K 
                Areas (Tables)                                                   
38: R28         Note 12 - Leases (Tables)                           HTML     27K 
39: R29         Note 3 - Stock-based Compensation (Details          HTML     39K 
                Textual)                                                         
40: R30         Note 3 - Stocked-based Compensation - Stock Option  HTML     42K 
                Activity (Details)                                               
41: R31         Note 5 - Inventories - Inventories (Details)        HTML     27K 
42: R32         Note 6 - Equity Investment in Unconsolidated        HTML     66K 
                Affiliate (Details Textual)                                      
43: R33         Note 7 - Accrued Liabilities - Accrued Liabilities  HTML     24K 
                (Details)                                                        
44: R34         Note 8 - Basic and Diluted Earnings Per Common      HTML     54K 
                Share - Reconciliation of Net Income and Number of               
                Shares Used in Computations of Basic and Diluted                 
                EPS (Details)                                                    
45: R35         Note 9 - Activity of Business Segments (Details     HTML     18K 
                Textual)                                                         
46: R36         Note 9 - Activity of Business Segments -            HTML     26K 
                Consolidated Net Sales (Details)                                 
47: R37         Note 9 - Activity of Business Segments -            HTML     41K 
                Reconciliation of Total Segment Income to Total                  
                Consolidated Net Income (Details)                                
48: R38         Note 9 - Activity of Business Segments -            HTML     25K 
                Consolidated Net Property and Equipment, Goodwill                
                and Intangible Assets (Details)                                  
49: R39         Note 10 - Financial Information about Geographic    HTML     23K 
                Areas (Details Textual)                                          
50: R40         Note 10 - Financial Information about Geographic    HTML     30K 
                Areas - Consolidated Net Sales and Long-lived                    
                Asset Information by Geographic Area (Details)                   
51: R41         Note 12 - Leases (Details Textual)                  HTML     29K 
52: R42         Note 12 - Leases - Future Minimum Lease Payment     HTML     31K 
                (Details)                                                        
53: R43         Note 14 - Contingencies (Details Textual)           HTML     21K 
56: XML         IDEA XML File -- Filing Summary                      XML    102K 
54: XML         XBRL Instance -- apt20220630_10q_htm                 XML    714K 
55: EXCEL       IDEA Workbook of Financial Reports                  XLSX     76K 
 7: EX-101.CAL  XBRL Calculations -- apt-20220630_cal                XML     96K 
 8: EX-101.DEF  XBRL Definitions -- apt-20220630_def                 XML    676K 
 9: EX-101.LAB  XBRL Labels -- apt-20220630_lab                      XML    503K 
10: EX-101.PRE  XBRL Presentations -- apt-20220630_pre               XML    711K 
 6: EX-101.SCH  XBRL Schema -- apt-20220630                          XSD    115K 
57: JSON        XBRL Instance as JSON Data -- MetaLinks              220±   349K 
58: ZIP         XBRL Zipped Folder -- 0001437749-22-019054-xbrl      Zip    140K

‘EX-101.DEF’ — XBRL Definitions — apt-20220630_def

This Exhibit is an XBRL XML File.

<?xml version="1.0" standalone="no" encoding="windows-1252"?>

<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" 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">

<link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple"/>

<link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple"/>

<link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple"/>

<link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple"/>

<link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple"/>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-15-subsequent-events" xlink:href="apt-20220630.xsd#statement-note-15-subsequent-events" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-15-subsequent-events" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisclosureTextBlockAbstract" xlink:label="us-gaap_DisclosureTextBlockAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventsTextBlock" xlink:label="us-gaap_SubsequentEventsTextBlock" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DisclosureTextBlockAbstract" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain-default" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DisclosureTextBlockAbstract" xlink:to="us-gaap_SubsequentEventsTextBlock" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-13-income-taxes" xlink:href="apt-20220630.xsd#statement-note-13-income-taxes" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-13-income-taxes" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisclosureTextBlockAbstract" xlink:label="us-gaap_DisclosureTextBlockAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeTaxDisclosureTextBlock" xlink:label="us-gaap_IncomeTaxDisclosureTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-11-related-party-transactions" xlink:href="apt-20220630.xsd#statement-note-11-related-party-transactions" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-11-related-party-transactions" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisclosureTextBlockAbstract" xlink:label="us-gaap_DisclosureTextBlockAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionsDisclosureTextBlock" xlink:label="us-gaap_RelatedPartyTransactionsDisclosureTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-4-recent-accounting-pronouncements" xlink:href="apt-20220630.xsd#statement-note-4-recent-accounting-pronouncements" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-4-recent-accounting-pronouncements" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisclosureTextBlockAbstract" xlink:label="us-gaap_DisclosureTextBlockAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock" xlink:label="us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-2-basis-of-presentation-and-revenue-recognition-policy" xlink:href="apt-20220630.xsd#statement-note-2-basis-of-presentation-and-revenue-recognition-policy" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-2-basis-of-presentation-and-revenue-recognition-policy" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisclosureTextBlockAbstract" xlink:label="us-gaap_DisclosureTextBlockAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SignificantAccountingPoliciesTextBlock" xlink:label="us-gaap_SignificantAccountingPoliciesTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-1-the-company" xlink:href="apt-20220630.xsd#statement-note-1-the-company" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-1-the-company" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisclosureTextBlockAbstract" xlink:label="us-gaap_DisclosureTextBlockAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NatureOfOperations" xlink:label="us-gaap_NatureOfOperations" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-condensed-consolidated-statements-of-shareholders-equity-unauditedparentheticals" xlink:href="apt-20220630.xsd#statement-condensed-consolidated-statements-of-shareholders-equity-unauditedparentheticals" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-condensed-consolidated-statements-of-shareholders-equity-unauditedparentheticals" xlink:type="extended">

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-condensed-consolidated-statements-of-comprehensive-income-unauditedparentheticals" xlink:href="apt-20220630.xsd#statement-condensed-consolidated-statements-of-comprehensive-income-unauditedparentheticals" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-condensed-consolidated-statements-of-comprehensive-income-unauditedparentheticals" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-condensed-consolidated-balance-sheets-unauditedparentheticals" xlink:href="apt-20220630.xsd#statement-condensed-consolidated-balance-sheets-unauditedparentheticals" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-condensed-consolidated-balance-sheets-unauditedparentheticals" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-document-and-entity-information" xlink:href="apt-20220630.xsd#statement-document-and-entity-information" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-document-and-entity-information" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_AmendmentFlag" xlink:label="dei_AmendmentFlag" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_CityAreaCode" xlink:label="dei_CityAreaCode" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_CurrentFiscalYearEndDate" xlink:label="dei_CurrentFiscalYearEndDate" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentFiscalPeriodFocus" xlink:label="dei_DocumentFiscalPeriodFocus" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentFiscalYearFocus" xlink:label="dei_DocumentFiscalYearFocus" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentInformationLineItems" xlink:label="dei_DocumentInformationLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentInformationTable" xlink:label="dei_DocumentInformationTable" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentPeriodEndDate" xlink:label="dei_DocumentPeriodEndDate" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentQuarterlyReport" xlink:label="dei_DocumentQuarterlyReport" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentTransitionReport" xlink:label="dei_DocumentTransitionReport" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentType" xlink:label="dei_DocumentType" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressAddressLine1" xlink:label="dei_EntityAddressAddressLine1" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressCityOrTown" xlink:label="dei_EntityAddressCityOrTown" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressCountry" xlink:label="dei_EntityAddressCountry" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressPostalZipCode" xlink:label="dei_EntityAddressPostalZipCode" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressStateOrProvince" xlink:label="dei_EntityAddressStateOrProvince" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityCentralIndexKey" xlink:label="dei_EntityCentralIndexKey" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityCommonStockSharesOutstanding" xlink:label="dei_EntityCommonStockSharesOutstanding" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityCurrentReportingStatus" xlink:label="dei_EntityCurrentReportingStatus" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityEmergingGrowthCompany" xlink:label="dei_EntityEmergingGrowthCompany" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityFileNumber" xlink:label="dei_EntityFileNumber" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityFilerCategory" xlink:label="dei_EntityFilerCategory" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityIncorporationStateCountryCode" xlink:label="dei_EntityIncorporationStateCountryCode" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityInteractiveDataCurrent" xlink:label="dei_EntityInteractiveDataCurrent" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityRegistrantName" xlink:label="dei_EntityRegistrantName" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityShellCompany" xlink:label="dei_EntityShellCompany" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntitySmallBusiness" xlink:label="dei_EntitySmallBusiness" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityTaxIdentificationNumber" xlink:label="dei_EntityTaxIdentificationNumber" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LocalPhoneNumber" xlink:label="dei_LocalPhoneNumber" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_Security12bTitle" xlink:label="dei_Security12bTitle" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_SecurityExchangeName" xlink:label="dei_SecurityExchangeName" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_TradingSymbol" xlink:label="dei_TradingSymbol" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="dei_DocumentInformationTable" xlink:to="dei_LegalEntityAxis" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentInformationTable" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityCentralIndexKey" xlink:type="arc"/>

<link:definitionArc order="2" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_AmendmentFlag" xlink:type="arc"/>

<link:definitionArc order="3" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_CurrentFiscalYearEndDate" xlink:type="arc"/>

<link:definitionArc order="4" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentFiscalYearFocus" xlink:type="arc"/>

<link:definitionArc order="5" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentFiscalPeriodFocus" xlink:type="arc"/>

<link:definitionArc order="6" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentType" xlink:type="arc"/>

<link:definitionArc order="7" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentQuarterlyReport" xlink:type="arc"/>

<link:definitionArc order="8" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentPeriodEndDate" xlink:type="arc"/>

<link:definitionArc order="9" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentTransitionReport" xlink:type="arc"/>

<link:definitionArc order="10" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityFileNumber" xlink:type="arc"/>

<link:definitionArc order="11" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityRegistrantName" xlink:type="arc"/>

<link:definitionArc order="12" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityIncorporationStateCountryCode" xlink:type="arc"/>

<link:definitionArc order="13" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityTaxIdentificationNumber" xlink:type="arc"/>

<link:definitionArc order="14" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityAddressAddressLine1" xlink:type="arc"/>

<link:definitionArc order="15" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityAddressCityOrTown" xlink:type="arc"/>

<link:definitionArc order="16" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityAddressStateOrProvince" xlink:type="arc"/>

<link:definitionArc order="17" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityAddressCountry" xlink:type="arc"/>

<link:definitionArc order="18" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityAddressPostalZipCode" xlink:type="arc"/>

<link:definitionArc order="19" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_CityAreaCode" xlink:type="arc"/>

<link:definitionArc order="20" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_LocalPhoneNumber" xlink:type="arc"/>

<link:definitionArc order="21" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_Security12bTitle" xlink:type="arc"/>

<link:definitionArc order="22" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_TradingSymbol" xlink:type="arc"/>

<link:definitionArc order="23" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_SecurityExchangeName" xlink:type="arc"/>

<link:definitionArc order="24" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityCurrentReportingStatus" xlink:type="arc"/>

<link:definitionArc order="25" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityInteractiveDataCurrent" xlink:type="arc"/>

<link:definitionArc order="26" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityFilerCategory" xlink:type="arc"/>

<link:definitionArc order="27" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntitySmallBusiness" xlink:type="arc"/>

<link:definitionArc order="28" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityEmergingGrowthCompany" xlink:type="arc"/>

<link:definitionArc order="29" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityShellCompany" xlink:type="arc"/>

<link:definitionArc order="30" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityCommonStockSharesOutstanding" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-condensed-consolidated-balance-sheets-unaudited" xlink:href="apt-20220630.xsd#statement-condensed-consolidated-balance-sheets-unaudited" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-condensed-consolidated-balance-sheets-unaudited" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountsPayableCurrent" xlink:label="us-gaap_AccountsPayableCurrent" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="us-gaap_AccountsReceivableNetCurrent" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountsReceivableRelatedPartiesCurrent" xlink:label="us-gaap_AccountsReceivableRelatedPartiesCurrent" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="us-gaap_AccruedLiabilitiesCurrent" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdditionalPaidInCapitalCommonStock" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsCurrent" xlink:label="us-gaap_AssetsCurrent" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsCurrentAbstract" xlink:label="us-gaap_AssetsCurrentAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="us-gaap_CommitmentsAndContingencies" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockValue" xlink:label="us-gaap_CommonStockValue" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:label="us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Goodwill" xlink:label="us-gaap_Goodwill" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InventoryNet" xlink:label="us-gaap_InventoryNet" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures" xlink:label="us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Liabilities" xlink:label="us-gaap_Liabilities" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesCurrent" xlink:label="us-gaap_LiabilitiesCurrent" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:label="us-gaap_LiabilitiesCurrentAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseLiabilityCurrent" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PrepaidExpenseCurrent" xlink:label="us-gaap_PrepaidExpenseCurrent" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="us-gaap_PropertyPlantAndEquipmentNet" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquity" xlink:label="us-gaap_StockholdersEquity" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquityAbstract" xlink:label="us-gaap_StockholdersEquityAbstract" xlink:type="locator"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AssetsCurrentAbstract" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_AccountsReceivableNetCurrent" xlink:type="arc"/>

<link:definitionArc order="2" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_AccountsReceivableRelatedPartiesCurrent" xlink:type="arc"/>

<link:definitionArc order="3" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_InventoryNet" xlink:type="arc"/>

<link:definitionArc order="4" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_PrepaidExpenseCurrent" xlink:type="arc"/>

<link:definitionArc order="5" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_AssetsCurrent" xlink:type="arc"/>

<link:definitionArc order="6" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_PropertyPlantAndEquipmentNet" xlink:type="arc"/>

<link:definitionArc order="7" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_Goodwill" xlink:type="arc"/>

<link:definitionArc order="8" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:type="arc"/>

<link:definitionArc order="9" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_OperatingLeaseRightOfUseAsset" xlink:type="arc"/>

<link:definitionArc order="10" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures" xlink:type="arc"/>

<link:definitionArc order="11" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_Assets" xlink:type="arc"/>

<link:definitionArc order="2" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LiabilitiesCurrentAbstract" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_AccountsPayableCurrent" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_AccruedLiabilitiesCurrent" xlink:type="arc"/>

<link:definitionArc order="2" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_OperatingLeaseLiabilityCurrent" xlink:type="arc"/>

<link:definitionArc order="3" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_LiabilitiesCurrent" xlink:type="arc"/>

<link:definitionArc order="4" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:type="arc"/>

<link:definitionArc order="5" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:type="arc"/>

<link:definitionArc order="6" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_Liabilities" xlink:type="arc"/>

<link:definitionArc order="7" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_CommitmentsAndContingencies" xlink:type="arc"/>

<link:definitionArc order="3" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockholdersEquityAbstract" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_CommonStockValue" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_AdditionalPaidInCapitalCommonStock" xlink:type="arc"/>

<link:definitionArc order="2" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit" xlink:type="arc"/>

<link:definitionArc order="3" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_StockholdersEquity" xlink:type="arc"/>

<link:definitionArc order="4" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_LiabilitiesAndStockholdersEquity" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-condensed-consolidated-balance-sheets-unauditedparentheticals-parentheticals" xlink:href="apt-20220630.xsd#statement-condensed-consolidated-balance-sheets-unauditedparentheticals-parentheticals" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-condensed-consolidated-balance-sheets-unauditedparentheticals-parentheticals" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="us-gaap_CommonStockSharesAuthorized" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="us-gaap_CommonStockSharesOutstanding" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:definitionArc order="4" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesOutstanding" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-condensed-consolidated-statements-of-comprehensive-income-unaudited" xlink:href="apt-20220630.xsd#statement-condensed-consolidated-statements-of-comprehensive-income-unaudited" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-condensed-consolidated-statements-of-comprehensive-income-unaudited" xlink:type="extended">

<link:loc xlink:href="apt-20220630.xsd#apt_GainLossOnFixedAssetsNonoperating" xlink:label="apt_GainLossOnFixedAssetsNonoperating" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CostOfGoodsAndServicesSold" xlink:label="us-gaap_CostOfGoodsAndServicesSold" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="us-gaap_DepreciationDepletionAndAmortization" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EarningsPerShareBasic" xlink:label="us-gaap_EarningsPerShareBasic" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="us-gaap_EarningsPerShareDiluted" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GrossProfit" xlink:label="us-gaap_GrossProfit" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeLossAttributableToParent" xlink:label="us-gaap_IncomeLossAttributableToParent" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeLossFromEquityMethodInvestments" xlink:label="us-gaap_IncomeLossFromEquityMethodInvestments" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="us-gaap_IncomeTaxExpenseBenefit" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestIncomeExpenseNonoperatingNet" xlink:label="us-gaap_InterestIncomeExpenseNonoperatingNet" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="us-gaap_NonoperatingIncomeExpense" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NonoperatingIncomeExpenseAbstract" xlink:label="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingExpenses" xlink:label="us-gaap_OperatingExpenses" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingExpensesAbstract" xlink:label="us-gaap_OperatingExpensesAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingIncomeLoss" xlink:label="us-gaap_OperatingIncomeLoss" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" xlink:label="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SellingGeneralAndAdministrativeExpense" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_DepreciationDepletionAndAmortization" xlink:type="arc"/>

<link:definitionArc order="2" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_OperatingExpenses" xlink:type="arc"/>

<link:definitionArc order="3" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_OperatingIncomeLoss" xlink:type="arc"/>

<link:definitionArc order="5" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="apt_GainLossOnFixedAssetsNonoperating" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_IncomeLossFromEquityMethodInvestments" xlink:type="arc"/>

<link:definitionArc order="2" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_InterestIncomeExpenseNonoperatingNet" xlink:type="arc"/>

<link:definitionArc order="3" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_NonoperatingIncomeExpense" xlink:type="arc"/>

<link:definitionArc order="4" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_IncomeLossAttributableToParent" xlink:type="arc"/>

<link:definitionArc order="5" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_IncomeTaxExpenseBenefit" xlink:type="arc"/>

<link:definitionArc order="6" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_NetIncomeLoss" xlink:type="arc"/>

<link:definitionArc order="7" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_EarningsPerShareBasic" xlink:type="arc"/>

<link:definitionArc order="8" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_EarningsPerShareDiluted" xlink:type="arc"/>

<link:definitionArc order="9" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:type="arc"/>

<link:definitionArc order="10" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-condensed-consolidated-statements-of-shareholders-equity-unaudited" xlink:href="apt-20220630.xsd#statement-condensed-consolidated-statements-of-shareholders-equity-unaudited" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-condensed-consolidated-statements-of-shareholders-equity-unaudited" xlink:type="extended">

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="us-gaap_AdditionalPaidInCapitalMember" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockMember" xlink:label="us-gaap_CommonStockMember" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="us-gaap_CommonStockSharesOutstanding" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RetainedEarningsMember" xlink:label="us-gaap_RetainedEarningsMember" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="us-gaap_StatementEquityComponentsAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares" xlink:label="us-gaap_StockRepurchasedAndRetiredDuringPeriodShares" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue" xlink:label="us-gaap_StockRepurchasedAndRetiredDuringPeriodValue" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquity" xlink:label="us-gaap_StockholdersEquity" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_CommonStockMember" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain-default" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AdditionalPaidInCapitalMember" xlink:type="arc"/>

<link:definitionArc order="2" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_RetainedEarningsMember" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" xlink:type="arc"/>

<link:definitionArc order="5" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockRepurchasedAndRetiredDuringPeriodValue" xlink:type="arc"/>

<link:definitionArc order="6" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:type="arc"/>

<link:definitionArc order="7" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:type="arc"/>

<link:definitionArc order="8" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-condensed-consolidated-statements-of-cash-flows-unaudited" xlink:href="apt-20220630.xsd#statement-condensed-consolidated-statements-of-cash-flows-unaudited" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-condensed-consolidated-statements-of-cash-flows-unaudited" xlink:type="extended">

<link:loc xlink:href="apt-20220630.xsd#apt_OperatingLeaseExpenseNetOfAccretion" xlink:label="apt_OperatingLeaseExpenseNetOfAccretion" xlink:type="locator"/>

<link:loc xlink:href="apt-20220630.xsd#apt_ProceedsFromPaymentsForStockOptionsExercised" xlink:label="apt_ProceedsFromPaymentsForStockOptionsExercised" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInContractWithCustomerLiability" xlink:label="us-gaap_IncreaseDecreaseInContractWithCustomerLiability" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInDueFromRelatedParties" xlink:label="us-gaap_IncreaseDecreaseInDueFromRelatedParties" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInInventories" xlink:label="us-gaap_IncreaseDecreaseInInventories" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInOperatingLeaseLiability" xlink:label="us-gaap_IncreaseDecreaseInOperatingLeaseLiability" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInPrepaidExpense" xlink:label="us-gaap_IncreaseDecreaseInPrepaidExpense" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensation" xlink:label="us-gaap_ShareBasedCompensation" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_NetIncomeLoss" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_ShareBasedCompensation" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_DepreciationDepletionAndAmortization" xlink:type="arc"/>

<link:definitionArc order="2" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_IncomeLossFromEquityMethodInvestments" xlink:type="arc"/>

<link:definitionArc order="3" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="apt_OperatingLeaseExpenseNetOfAccretion" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="us-gaap_IncreaseDecreaseInDueFromRelatedParties" xlink:type="arc"/>

<link:definitionArc order="2" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="us-gaap_IncreaseDecreaseInInventories" xlink:type="arc"/>

<link:definitionArc order="3" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="us-gaap_IncreaseDecreaseInPrepaidExpense" xlink:type="arc"/>

<link:definitionArc order="4" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:type="arc"/>

<link:definitionArc order="5" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="us-gaap_IncreaseDecreaseInContractWithCustomerLiability" xlink:type="arc"/>

<link:definitionArc order="6" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="us-gaap_IncreaseDecreaseInOperatingLeaseLiability" xlink:type="arc"/>

<link:definitionArc order="7" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:type="arc"/>

<link:definitionArc order="5" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="apt_ProceedsFromPaymentsForStockOptionsExercised" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:type="arc"/>

<link:definitionArc order="2" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:type="arc"/>

<link:definitionArc order="3" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:type="arc"/>

<link:definitionArc order="4" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-3-stockbased-compensation" xlink:href="apt-20220630.xsd#statement-note-3-stockbased-compensation" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-3-stockbased-compensation" xlink:type="extended">

<link:loc xlink:href="apt-20220630.xsd#apt_IncentivePlan2020Member" xlink:label="apt_IncentivePlan2020Member" xlink:type="locator"/>

<link:loc xlink:href="apt-20220630.xsd#apt_The2004PlanMember" xlink:label="apt_The2004PlanMember" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisclosureTextBlockAbstract" xlink:label="us-gaap_DisclosureTextBlockAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="us-gaap_EmployeeStockOptionMember" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameAxis" xlink:label="us-gaap_PlanNameAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestrictedStockMember" xlink:label="us-gaap_RestrictedStockMember" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestructuringPlanAxis" xlink:label="us-gaap_RestructuringPlanAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestructuringPlanDomain" xlink:label="us-gaap_RestructuringPlanDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestructuringPlanDomain" xlink:label="us-gaap_RestructuringPlanDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RestructuringPlanAxis" xlink:to="us-gaap_RestructuringPlanDomain" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringPlanDomain" xlink:to="apt_IncentivePlan2020Member" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RestructuringPlanAxis" xlink:to="us-gaap_RestructuringPlanDomain-default" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_PlanNameAxis" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanNameDomain" xlink:to="apt_The2004PlanMember" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain-default" xlink:type="arc"/>

<link:definitionArc order="2" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_AwardTypeAxis" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_EmployeeStockOptionMember" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain-default" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanNameDomain" xlink:to="apt_IncentivePlan2020Member" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_RestrictedStockMember" xlink:type="arc"/>

<link:definitionArc order="3" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-5-inventories" xlink:href="apt-20220630.xsd#statement-note-5-inventories" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-5-inventories" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisclosureTextBlockAbstract" xlink:label="us-gaap_DisclosureTextBlockAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InventoryDisclosureTextBlock" xlink:label="us-gaap_InventoryDisclosureTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-6-equity-investment-in-unconsolidated-affiliate" xlink:href="apt-20220630.xsd#statement-note-6-equity-investment-in-unconsolidated-affiliate" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-6-equity-investment-in-unconsolidated-affiliate" xlink:type="extended">

<link:loc xlink:href="apt-20220630.xsd#apt_AlphaProTechEngineeredProductsMember" xlink:label="apt_AlphaProTechEngineeredProductsMember" xlink:type="locator"/>

<link:loc xlink:href="apt-20220630.xsd#apt_HarmonyMember" xlink:label="apt_HarmonyMember" xlink:type="locator"/>

<link:loc xlink:href="apt-20220630.xsd#apt_ManufacturingBuildingProductsMember" xlink:label="apt_ManufacturingBuildingProductsMember" xlink:type="locator"/>

<link:loc xlink:href="apt-20220630.xsd#apt_ManufacturingCoatedMaterialAndSewingProprietaryDisposableProtectiveApparelMember" xlink:label="apt_ManufacturingCoatedMaterialAndSewingProprietaryDisposableProtectiveApparelMember" xlink:type="locator"/>

<link:loc xlink:href="apt-20220630.xsd#apt_ManufacturingOfBuildingProductsMember" xlink:label="apt_ManufacturingOfBuildingProductsMember" xlink:type="locator"/>

<link:loc xlink:href="apt-20220630.xsd#apt_MapleIndustriesAndAssociatesMember" xlink:label="apt_MapleIndustriesAndAssociatesMember" xlink:type="locator"/>

<link:loc xlink:href="apt-20220630.xsd#apt_SewingProprietaryDisposableProtectiveApparelMember" xlink:label="apt_SewingProprietaryDisposableProtectiveApparelMember" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/country/2022/country-2022.xsd#country_IN" xlink:label="country_IN" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivablesByLegalEntityOfCounterpartyTypeAxis" xlink:label="us-gaap_AccountsNotesLoansAndFinancingReceivablesByLegalEntityOfCounterpartyTypeAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisclosureTextBlockAbstract" xlink:label="us-gaap_DisclosureTextBlockAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentsDisclosureTextBlock" xlink:label="us-gaap_EquityMethodInvestmentsDisclosureTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LegalEntityTypeOfCounterpartyDomain" xlink:label="us-gaap_LegalEntityTypeOfCounterpartyDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AccountsNotesLoansAndFinancingReceivablesByLegalEntityOfCounterpartyTypeAxis" xlink:to="us-gaap_LegalEntityTypeOfCounterpartyDomain" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="apt_HarmonyMember" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain-default" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LegalEntityTypeOfCounterpartyDomain" xlink:to="apt_AlphaProTechEngineeredProductsMember" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AccountsNotesLoansAndFinancingReceivablesByLegalEntityOfCounterpartyTypeAxis" xlink:to="us-gaap_LegalEntityTypeOfCounterpartyDomain-default" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LegalEntityTypeOfCounterpartyDomain" xlink:to="apt_MapleIndustriesAndAssociatesMember" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="country_IN" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain-default" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="apt_HarmonyMember" xlink:type="arc"/>

<link:definitionArc order="4" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="srt_ProductOrServiceAxis" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="apt_ManufacturingBuildingProductsMember" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain-default" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="apt_ManufacturingCoatedMaterialAndSewingProprietaryDisposableProtectiveApparelMember" xlink:type="arc"/>

<link:definitionArc order="2" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="apt_SewingProprietaryDisposableProtectiveApparelMember" xlink:type="arc"/>

<link:definitionArc order="3" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="apt_ManufacturingOfBuildingProductsMember" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-7-accrued-liabilities" xlink:href="apt-20220630.xsd#statement-note-7-accrued-liabilities" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-7-accrued-liabilities" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock" xlink:label="us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisclosureTextBlockAbstract" xlink:label="us-gaap_DisclosureTextBlockAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-8-basic-and-diluted-earnings-per-common-share" xlink:href="apt-20220630.xsd#statement-note-8-basic-and-diluted-earnings-per-common-share" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-8-basic-and-diluted-earnings-per-common-share" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisclosureTextBlockAbstract" xlink:label="us-gaap_DisclosureTextBlockAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EarningsPerShareTextBlock" xlink:label="us-gaap_EarningsPerShareTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-9-activity-of-business-segments" xlink:href="apt-20220630.xsd#statement-note-9-activity-of-business-segments" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-9-activity-of-business-segments" xlink:type="extended">

<link:loc xlink:href="apt-20220630.xsd#apt_BuildingSupplyMember" xlink:label="apt_BuildingSupplyMember" xlink:type="locator"/>

<link:loc xlink:href="apt-20220630.xsd#apt_DisposableProtectiveApparelMember" xlink:label="apt_DisposableProtectiveApparelMember" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="us-gaap_CorporateNonSegmentMember" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisclosureTextBlockAbstract" xlink:label="us-gaap_DisclosureTextBlockAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingSegmentsMember" xlink:label="us-gaap_OperatingSegmentsMember" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SegmentReportingDisclosureTextBlock" xlink:label="us-gaap_SegmentReportingDisclosureTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_OperatingSegmentsMember" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain-default" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="apt_BuildingSupplyMember" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain-default" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="apt_DisposableProtectiveApparelMember" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_CorporateNonSegmentMember" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-10-financial-information-about-geographic-areas" xlink:href="apt-20220630.xsd#statement-note-10-financial-information-about-geographic-areas" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-10-financial-information-about-geographic-areas" xlink:type="extended">

<link:loc xlink:href="apt-20220630.xsd#apt_FinancialInformationAboutGeographicAreasTextBlock" xlink:label="apt_FinancialInformationAboutGeographicAreasTextBlock" xlink:type="locator"/>

<link:loc xlink:href="apt-20220630.xsd#apt_InternationalMember" xlink:label="apt_InternationalMember" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/country/2022/country-2022.xsd#country_CA" xlink:label="country_CA" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/country/2022/country-2022.xsd#country_US" xlink:label="country_US" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ReportableGeographicalComponentsMember" xlink:label="srt_ReportableGeographicalComponentsMember" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisclosureTextBlockAbstract" xlink:label="us-gaap_DisclosureTextBlockAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ConsolidationItemsDomain" xlink:to="srt_ReportableGeographicalComponentsMember" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="apt_InternationalMember" xlink:type="arc"/>

<link:definitionArc order="2" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="country_CA" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DisclosureTextBlockAbstract" xlink:to="apt_FinancialInformationAboutGeographicAreasTextBlock" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-12-leases-" xlink:href="apt-20220630.xsd#statement-note-12-leases-" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-12-leases-" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisclosureTextBlockAbstract" xlink:label="us-gaap_DisclosureTextBlockAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeOperatingLeasesTextBlock" xlink:label="us-gaap_LesseeOperatingLeasesTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-14-contingencies" xlink:href="apt-20220630.xsd#statement-note-14-contingencies" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-14-contingencies" xlink:type="extended">

<link:loc xlink:href="apt-20220630.xsd#apt_LawsuitWithDefendantsInUtahForUndeliveredEquipmentMember" xlink:label="apt_LawsuitWithDefendantsInUtahForUndeliveredEquipmentMember" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_LitigationCaseAxis" xlink:label="srt_LitigationCaseAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_LitigationCaseTypeDomain" xlink:label="srt_LitigationCaseTypeDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_LitigationCaseTypeDomain" xlink:label="srt_LitigationCaseTypeDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisclosureTextBlockAbstract" xlink:label="us-gaap_DisclosureTextBlockAbstract" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_LitigationCaseAxis" xlink:to="srt_LitigationCaseTypeDomain" xlink:type="arc"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_LitigationCaseTypeDomain" xlink:to="apt_LawsuitWithDefendantsInUtahForUndeliveredEquipmentMember" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_LitigationCaseAxis" xlink:to="srt_LitigationCaseTypeDomain-default" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-3-stockbased-compensation-tables" xlink:href="apt-20220630.xsd#statement-note-3-stockbased-compensation-tables" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-3-stockbased-compensation-tables" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:label="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TableTextBlock" xlink:label="us-gaap_TableTextBlock" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TableTextBlock" xlink:to="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-5-inventories-tables" xlink:href="apt-20220630.xsd#statement-note-5-inventories-tables" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-5-inventories-tables" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfInventoryCurrentTableTextBlock" xlink:label="us-gaap_ScheduleOfInventoryCurrentTableTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TableTextBlock" xlink:label="us-gaap_TableTextBlock" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TableTextBlock" xlink:to="us-gaap_ScheduleOfInventoryCurrentTableTextBlock" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-7-accrued-liabilities-tables" xlink:href="apt-20220630.xsd#statement-note-7-accrued-liabilities-tables" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-7-accrued-liabilities-tables" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock" xlink:label="us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TableTextBlock" xlink:label="us-gaap_TableTextBlock" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TableTextBlock" xlink:to="us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-8-basic-and-diluted-earnings-per-common-share-tables" xlink:href="apt-20220630.xsd#statement-note-8-basic-and-diluted-earnings-per-common-share-tables" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-8-basic-and-diluted-earnings-per-common-share-tables" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" xlink:label="us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TableTextBlock" xlink:label="us-gaap_TableTextBlock" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TableTextBlock" xlink:to="us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-9-activity-of-business-segments-tables" xlink:href="apt-20220630.xsd#statement-note-9-activity-of-business-segments-tables" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-9-activity-of-business-segments-tables" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTextBlock" xlink:label="us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTextBlock" xlink:label="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TableTextBlock" xlink:label="us-gaap_TableTextBlock" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TableTextBlock" xlink:to="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" xlink:type="arc"/>

<link:definitionArc order="1" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TableTextBlock" xlink:to="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTextBlock" xlink:type="arc"/>

<link:definitionArc order="2" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TableTextBlock" xlink:to="us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTextBlock" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-10-financial-information-about-geographic-areas-tables" xlink:href="apt-20220630.xsd#statement-note-10-financial-information-about-geographic-areas-tables" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-10-financial-information-about-geographic-areas-tables" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsByGeographicalAreasTableTextBlock" xlink:label="us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsByGeographicalAreasTableTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TableTextBlock" xlink:label="us-gaap_TableTextBlock" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TableTextBlock" xlink:to="us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsByGeographicalAreasTableTextBlock" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-12-leases-tables" xlink:href="apt-20220630.xsd#statement-note-12-leases-tables" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-12-leases-tables" xlink:type="extended">

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TableTextBlock" xlink:label="us-gaap_TableTextBlock" xlink:type="locator"/>

<link:definitionArc order="0" xbrldt:closed="true" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TableTextBlock" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:type="arc"/>

</link:definitionLink>

<link:roleRef roleURI="http://www.alphaprotech.com/20220630/role/statement-note-3-stockbased-compensation-details-textual" xlink:href="apt-20220630.xsd#statement-note-3-stockbased-compensation-details-textual" xlink:type="simple"/>

<link:definitionLink xlink:role="http://www.alphaprotech.com/20220630/role/statement-note-3-stockbased-compensation-details-textual" xlink:type="extended">

<link:loc xlink:href="apt-20220630.xsd#apt_IncentivePlan2020Member" xlink:label="apt_IncentivePlan2020Member" xlink:type="locator"/>

<link:loc xlink:href="apt-20220630.xsd#apt_The2004PlanMember" xlink:label="apt_The2004PlanMember" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain-default" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:label="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:type="locator"/>

<link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:type="locator"/>