caustic

Short definition from Wiktionary

Adjective

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

Noun

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