apropos vs notional

apropos

adj
  • Of an appropriate or pertinent nature. 

  • by the way, incidental 

prep
  • Regarding or concerning. 

adv
  • To the purpose; appropriately. 

  • By the way. 

  • Timely; at a good time. 

notional

adj
  • Of, containing, or being a notion; mental or imaginary. 

  • Having descriptive value as opposed to a syntactic category. 

  • Used to indicate an estimate or a reference amount 

  • Full of ideas or imaginings. 

  • Speculative, theoretical, not the result of research. 

noun
  • A fake company used as a front in espionage. 

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