apropos vs opportune

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. 

opportune

adj
  • Suitable for some particular purpose. 

  • At a convenient or advantageous time. 

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