caustic vs smouldering

caustic

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

  • 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. 

adj
  • Capable of burning, corroding or destroying organic tissue. 

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

smouldering

noun
  • The act by which something smoulders; residual heat. 

adj
  • Burning slowly, producing smoke but no flame. 

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