Noah Webster
Caustic
CAUSTIC,
CAUSTICAL, adjective Burning; corroding; destroying the texture of animal flesh.
CAUSTIC, noun In medicine, any substance which applied to living animals, acts like fire, in corroding the part and dissolving its texture; an escharotic. [See Causticity.]
Lunar caustic a preparation of crystals of silver, obtained by solution in nitric acid, and afterwards fused in a crucible. It is a nitrate of silver.
CAUSTIC curve, in geometry, a curve formed by a coincidence of rays of light reflected from another curve.