acerbate vs grim

acerbate

verb
  • To make bitter or sour. 

  • To exasperate; to irritate. 

adj
  • Embittered; having a sour disposition or nature. 

grim

verb
  • To make grim; to give a stern or forbidding aspect to. 

adj
  • Rigid and unrelenting. 

  • Ghastly or sinister. 

  • Disgusting; gross. 

  • Dismal and gloomy, cold and forbidding. 

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