acrid vs caustic

acrid

adj
  • Caustic; bitter; bitterly irritating. 

  • Causing heat and irritation. 

  • Sharp and harsh, or bitter and not to the taste. 

caustic

adj
  • Sharp, bitter, cutting, biting, and sarcastic in a scathing way. 

  • Capable of burning, corroding or destroying organic tissue. 

noun
  • The envelope of reflected or refracted rays for a given curve. 

  • Caustic soda. 

  • The envelope of reflected or refracted rays of light for a given surface or object. 

  • Any substance or means which, applied to animal or other organic tissue, burns, corrodes, or destroys it by chemical action; an escharotic. 

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