acerbate vs execrate

acerbate

verb
  • To make bitter or sour. 

  • To exasperate; to irritate. 

adj
  • Embittered; having a sour disposition or nature. 

execrate

verb
  • to feel loathing for; to abhor 

  • to declare to be hateful or abhorrent; to denounce 

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