Definition from Wiktionary, the free dictionary
- enPR: kôs'tĭk, kŏs'tĭk, IPA: /ˈkɔːstɪk/, /ˈkɒstɪk/, X-SAMPA: /"kO:stIk/, /"kQstIk/
Audio (US) (file)
- Rhymes: -ɔːstɪk
- Capable of burning, corroding or destroying organic tissue
- (of language etc) sharp, bitter, cutting, biting, sarcastic
- (capable of destroying tissue): acidic, biting, burning, corrosive, searing
- (severe, sharp): bitchy, biting, catty, mordacious, nasty, sharp, spiteful
- 1843: "How now!" said Scrooge, caustic and cold as ever. — Charles Dickens, A Christmas Carol
- 1843: 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 — Charles Dickens, Martin Chuzzlewit
- 1853: Madame Beck esteemed me learned and blue; Miss Fanshawe, caustic, ironic, and cynical — Charlotte Bronte, Villette
- 1857: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. — Anthony Trollope, The Three Clerks
- 1886: this set of worthies, who were only too prone to shut up their emotions with caustic words. — Thomas Hardy, The Mayor of Casterbridge
- 1930s???: though he came too late / To join the martyrs, there was still a place / Among the tempters for a caustic tongue / / To test the resolution of the young / With tales of the small failings of the great — W.H.Auden, 'The Quest'
Derived terms 
capable of destroying organic tissue
severe; satirical; sharp
caustic (plural caustics)
- Any substance or means which, applied to animal or other organic tissue, burns, corrodes, or destroys it by chemical action; an escharotic.
- (optics, computer graphics) The envelope of reflected or refracted rays of light for a given surface or object.
- (mathematics) The envelope of reflected or refracted rays for a given curve.
- (informal, chemistry) caustic soda
Derived terms 
substance which burns, corrodes or destroys organic tissue
envelope of reflected or refracted rays of light for a given surface or object