apropos vs especially

apropos

adv
  • To the purpose; appropriately. 

  • By the way. 

  • Timely; at a good time. 

adj
  • Of an appropriate or pertinent nature. 

  • by the way, incidental 

prep
  • Regarding or concerning. 

especially

adv
  • In a special manner; specially. 

  • Used to place greater emphasis upon someone or something. 

  • Particularly; to a greater extent than is normal. 

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