acerbate vs hack off

acerbate

verb
  • To exasperate; to irritate. 

  • To make bitter or sour. 

adj
  • Embittered; having a sour disposition or nature. 

hack off

verb
  • To annoy 

  • To remove by hacking; to cut off 

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