basal vs extrinsic

basal

noun
  • base, bottom, minimum 

  • Any basal structure or part 

adj
  • Basic, elementary; relating to, or forming, the base, or point of origin. 

  • In a phylogenetic tree, being a group, or member of a group, which diverged earlier. The earliest clade to branch in a larger clade. 

  • Associated with the base of an organism or structure. 

  • Of a minimal level that is necessary for maintaining the health or life of an organism. 

extrinsic

noun
  • An external factor 

adj
  • external; separable from the thing itself; inessential 

  • not belonging to something; outside 

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