acerbate vs brutalise

acerbate

verb
  • To make bitter or sour. 

  • To exasperate; to irritate. 

adj
  • Embittered; having a sour disposition or nature. 

brutalise

verb
  • To make brutal, cruel or harsh. 

  • To inflict brutal violence on. 

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