accessory vs retrofit

accessory

noun
  • Something that belongs to part of another main thing; something additional and subordinate, an attachment. 

  • Something in a work of art without being indispensably necessary, for example solely ornamental parts. 

  • An article that completes one's basic outfit, such as a scarf or gloves. 

  • A person who is not present at a crime, but contributes to it as an assistant or instigator. 

adj
  • Having a secondary, supplementary or subordinate function by accompanying as a subordinate; aiding in a secondary way; being additional; contributing or being contributory. Said of things and actions, very rarely of people (and then usually in a humorous version of the legal sense [or due to confusion between the noun and the adjective]). 

  • Assisting a crime without actually participating in committing the crime itself; being connected as an incident or subordinate to a principal. 

  • Present in a minor amount, and not essential. 

retrofit

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. 

verb
  • 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. 

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

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