caustic
\KAW-stik\
adjective
1. severely critical or sarcastic: a caustic remark.
2. capable of burning, corroding, or destroying living tissue.
Quotes
Osborne reddened, and was on the point of letting fly some caustic remark on his father's dress at the present moment; but he contented himself with saying, in a low voice, "My mother always expected us all to dress for dinner…"
-- Elizabeth Gaskell, Wives and Daughters, 1866
Origin
Caustic has been in English since the 1300s. It comes from the Greek word kaustikós, meaning "burning."
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