acerbate vs agonize

acerbate

verb
  • To make bitter or sour. 

  • To exasperate; to irritate. 

adj
  • Embittered; having a sour disposition or nature. 

agonize

verb
  • To writhe with agony; to suffer violent anguish. 

  • To struggle; to wrestle; to strive desperately, whether mentally or physically. 

  • To cause agony or anguish in someone. 

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