extensional vs unlikely

extensional

adj
  • Of or pertaining to extension. 

  • Having great extent. 

unlikely

adj
  • Not holding out a prospect of success; likely to fail; unpromising. 

  • Not likely; improbable; not to be reasonably expected. 

adv
  • In an improbable manner. 

noun
  • Something or somebody considered unlikely. 

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