extramural vs extrinsic

extramural

adj
  • Taking place outside the walls of an institution, especially a school or university. 

  • Describing teaching of students who are not resident at such an institution. 

extrinsic

adj
  • not belonging to something; outside 

  • external; separable from the thing itself; inessential 

noun
  • An external factor 

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