apropos vs unrelated

apropos

adv
  • To the purpose; appropriately. 

  • By the way. 

  • Timely; at a good time. 

prep
  • Regarding or concerning. 

adj
  • Of an appropriate or pertinent nature. 

  • by the way, incidental 

unrelated

adj
  • not related by kinship 

  • not connected or associated 

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