<?xml version='1.0' encoding='utf-8'?>
<!-- Created by Charles Hoffman, CPA 2020-02-16 -->
<!-- Public Domain Dedication: https://creativecommons.org/publicdomain/zero/1.0/ -->
<!-- NOTE that arcrole from DISCLOSURE to REQUIRED CONCEPT rather than from CONCEPT ARRANGMENT PATTERN to REQUIRED CONCEPT -->
<link:linkbase
    xmlns='http://www.xbrl.org/2003/linkbase'
    xmlns:xbrldt='http://xbrl.org/2005/xbrldt'
    xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
    xmlns:xlink='http://www.w3.org/1999/xlink'
    xmlns:link='http://www.xbrl.org/2003/linkbase'
    xsi:schemaLocation='http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd'>

   <link:roleRef xlink:type='simple' xlink:href='dm-extended-link-roles.xsd#RevenueRecognitionPolicy' roleURI='http://www.xbrlsite.com/2020/elr/role/DisclosureMechanics/RevenueRecognitionPolicy'/>

   <link:arcroleRef xlink:type='simple' xlink:href='http://xbrlsite.azurewebsites.net/2016/conceptual-model/drules-arcroles.xsd#disclosure-hasConceptArrangementPattern' arcroleURI='http://xbrlsite.azurewebsites.net/2016/conceptual-model/drules-arcroles/arcrole/disclosure-hasConceptArrangementPattern'/>
   <link:arcroleRef xlink:type='simple' xlink:href='http://xbrlsite.azurewebsites.net/2016/conceptual-model/drules-arcroles.xsd#disclosure-requiresHypercube' arcroleURI='http://xbrlsite.azurewebsites.net/2016/conceptual-model/drules-arcroles/arcrole/disclosure-requiresHypercube'/>
   <link:arcroleRef xlink:type='simple' xlink:href='http://xbrlsite.azurewebsites.net/2016/conceptual-model/drules-arcroles.xsd#disclosure-requiresConcept' arcroleURI='http://xbrlsite.azurewebsites.net/2016/conceptual-model/drules-arcroles/arcrole/disclosure-requiresConcept'/>
   <link:arcroleRef xlink:type='simple' xlink:href='http://xbrlsite.azurewebsites.net/2016/conceptual-model/drules-arcroles.xsd#conceptArrangementPattern-requiresConcept' arcroleURI='http://xbrlsite.azurewebsites.net/2016/conceptual-model/drules-arcroles/arcrole/conceptArrangementPattern-requiresConcept'/>
   <link:arcroleRef xlink:type='simple' xlink:href='http://xbrlsite.azurewebsites.net/2016/conceptual-model/drules-arcroles.xsd#disclosure-equivalentTextblock' arcroleURI='http://xbrlsite.azurewebsites.net/2016/conceptual-model/drules-arcroles/arcrole/disclosure-equivalentTextblock'/>


   <link:definitionLink xlink:type='extended' xlink:role='http://www.xbrlsite.com/2020/elr/role/DisclosureMechanics/RevenueRecognitionPolicy' xlink:title='A representation of this disclosure will always include this hypercube'>
      <link:loc xlink:type='locator' xlink:href='disclosures.xsd#disclosures_RevenueRecognitionPolicy' xlink:label='disclosures_RevenueRecognitionPolicy' />
      <link:loc xlink:type='locator' xlink:href='proof.xsd#proof_PoliciesHypercube' xlink:label='proof_PoliciesHypercube' />
      <link:definitionArc xlink:type='arc' xlink:arcrole='http://xbrlsite.azurewebsites.net/2016/conceptual-model/drules-arcroles/arcrole/disclosure-requiresHypercube' xlink:from='disclosures_RevenueRecognitionPolicy' xlink:to='proof_PoliciesHypercube' order='1' use='optional' />
   </link:definitionLink>

   <link:definitionLink xlink:type='extended' xlink:role='http://www.xbrlsite.com/2020/elr/role/DisclosureMechanics/RevenueRecognitionPolicy' xlink:title='This RevenueRecognitionPolicy disclosure is a TextBlock concept arrangment pattern.'>
      <link:loc xlink:type='locator' xlink:href='disclosures.xsd#disclosures_RevenueRecognitionPolicy' xlink:label='disclosures_RevenueRecognitionPolicy' />
      <link:loc xlink:type='locator' xlink:href='http://xbrlsite.azurewebsites.net/2016/conceptual-model/cm.xsd#cm_Level1TextBlock' xlink:label='cm_Level1TextBlock' />
      <link:definitionArc xlink:type='arc' xlink:arcrole='http://xbrlsite.azurewebsites.net/2016/conceptual-model/drules-arcroles/arcrole/disclosure-hasConceptArrangementPattern' xlink:from='disclosures_RevenueRecognitionPolicy' xlink:to='cm_Level1TextBlock' order='2' use='optional' />
   </link:definitionLink>


   <link:definitionLink xlink:type='extended' xlink:role='http://www.xbrlsite.com/2020/elr/role/DisclosureMechanics/RevenueRecognitionPolicy' xlink:title='The RevenueRecognitionPolicy disclosure requires the fact RevenueRecognitionPolicyTextBlock to be reported.'>
     <link:loc xlink:type='locator' xlink:href='disclosures.xsd#disclosures_RevenueRecognitionPolicy' xlink:label='disclosures_RevenueRecognitionPolicy' />
      <link:loc xlink:type='locator' xlink:href='proof.xsd#proof_RevenueRecognitionPolicyTextBlock' xlink:label='proof_RevenueRecognitionPolicyTextBlock' />
      <link:definitionArc xlink:type='arc' xlink:arcrole='http://xbrlsite.azurewebsites.net/2016/conceptual-model/drules-arcroles/arcrole/disclosure-equivalentTextblock' xlink:from='disclosures_RevenueRecognitionPolicy' xlink:to='proof_RevenueRecognitionPolicyTextBlock' order='3' use='optional' />
   </link:definitionLink>


</link:linkbase>
