extraneous vs extrinsic

extraneous

adj
  • Not belonging to, or dependent upon, a thing; without or beyond a thing; foreign 

  • Not essential or intrinsic 

extrinsic

adj
  • not belonging to something; outside 

  • external; separable from the thing itself; inessential 

noun
  • An external factor 

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