caustic

adj

1. Capable of burning, corroding or destroying organic tissue.
2. (usually)Sharp, bitter, cutting, biting, and sarcastic in a scathing way.

   “"How now!" said Scrooge, caustic and cold as ever.”

   “The bargain was not concluded as easily as might have been expected though, for Scadder was caustic and ill-humoured, and cast much unnecessary opposition in the way”

   “Madame Beck esteemed me learned and blue; Miss Fanshawe, caustic, ironic, and cynical”

   “The Secretary and the Assistant-Secretaries would say little caustic things about him to the senior clerks, and seemed somewhat to begrudge him his new honours.”

   “this set of worthies, who were only too prone to shut up their emotions with caustic words.”

noun

1. (countable, uncountable)Any substance or means which, applied to animal or other organic tissue, burns, corrodes, or destroys it by chemical action; an escharotic.
2. (countable, uncountable)The envelope of reflected or refracted rays of light for a given surface or object.
3. (countable, uncountable)The envelope of reflected or refracted rays for a given curve.
4. (informal, uncountable)Caustic soda.