acerbate vs pettish

acerbate

adj
  • Embittered; having a sour disposition or nature. 

verb
  • To exasperate; to irritate. 

  • To make bitter or sour. 

pettish

adj
  • bad-tempered; peevish 

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