Caustic means burning to the skin, or bitingly sarcastic. A caustic remark, caustic soda, caustic wit.
Caustic soda is the household name for sodium hydroxide, which burns and is used to clear drains. The figurative sense is admiring as often as not, since a caustic wit is a compliment to everybody but its target.
1adjectivecausticBurning to the skin, or bitingly sarcastic.
“Wear gloves, because this cleaner is caustic and can burn your skin.”
caustic is a quality.
Greek kaustikos means burning, from kaiein, to burn.
Ancient Greek
καυστικός — burning
Latin
causticus — burning
English, today
caustic
From the Latin causticus (“burning”), from Ancient Greek καυστικός (“burning”), from καυστός + ικός.
Etymology from Wiktionary, CC BY-SA