say it: KAH-stik
caustic is an adjective and noun meaning "harsh or corrosive in tone". It carries 3 recorded senses.
harsh or corrosive in tone
“an acerbic tone piercing otherwise flowery prose”
“a barrage of acid comments”
“her acrid remarks make her many enemies”
“bitter words”
“blistering criticism”
“caustic jokes about political assassination, talk-show hosts and medical ethics”
“a sulfurous denunciation”
“a vitriolic critique”
of a substance, especially a strong acid; capable of destroying or eating away by chemical action
any chemical substance that burns or destroys living tissue
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for caustic come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.