acerbate vs ruffle someone's feathers

acerbate

verb
  • To exasperate; to irritate. 

  • To make bitter or sour. 

adj
  • Embittered; having a sour disposition or nature. 

ruffle someone's feathers

verb
  • To unease, cause discomfort to someone. 

How often have the words acerbate and ruffle someone's feathers occurred in a corpus of books? (source: Google Ngram Viewer )