integrate vs retrofit

integrate

verb
  • To combine compatible elements in order to incorporate them. 

  • To subject to the operation of integration; to find the integral of an equation. 

  • To desegregate, as a school or neighborhood. 

  • To include as a constituent part or functionality. 

  • To indicate the whole of; to give the sum or total of; as, an integrating anemometer, one that indicates or registers the entire action of the wind in a given time. 

  • To form into one whole; to make entire; to complete; to renew; to restore; to perfect. 

retrofit

verb
  • To add or substitute (new components or parts) that were not previously available for or installed in a device, structure, etc. 

  • To supply (a device, structure, etc.) with new components or parts that were not previously available or installed; to modernize. 

  • Synonym of backport (“to retroactively supply a fix or feature to a previous version of a software product at the same time or after supplying it to the current version.”) 

  • To give new characteristics or make alterations (to someone or something) to suit them to changed circumstances. 

  • To supply a device, structure, etc., with new components or parts that were not previously available or installed. 

noun
  • An act of supplying a device, structure, etc., with new components or parts that were not previously available or installed; a retrofitting. 

  • A change made to a device, structure, etc., by introducing components or parts that were not previously available or installed. 

How often have the words integrate and retrofit occurred in a corpus of books? (source: Google Ngram Viewer )