acerbate vs repel

acerbate

verb
  • To exasperate; to irritate. 

  • To make bitter or sour. 

adj
  • Embittered; having a sour disposition or nature. 

repel

verb
  • To cause repulsion or dislike in; to disgust. 

  • To ward off (a malignant influence, attack etc.). 

  • To drive back (an assailant, advancing force etc.). 

  • To reject, put off (a request, demand etc.). 

  • To save (a shot). 

  • To force away by means of a repulsive force. 

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