crucial vs extrinsic

crucial

adj
  • Very good; excellent; particularly applied to reggae music. 

  • Essential or decisive for determining the outcome or future of something; extremely important; vital. 

extrinsic

adj
  • external; separable from the thing itself; inessential 

  • not belonging to something; outside 

noun
  • An external factor 

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