Caus·tic Caus·tic·al a.
 1. Capable of destroying the texture of anything or eating away its substance by chemical action; burning; corrosive; searing.
 2. Severe; satirical; sharp; as, a caustic remark.
 Caustic curve Optics, a curve to which the ray of light, reflected or refracted by another curve, are tangents, the reflecting or refracting curve and the luminous point being in one plane.
 Caustic lime. See under Lime.
 Caustic potash, Caustic soda Chem., the solid hydroxides potash, KOH, and soda, NaOH, or solutions of the same.
 Caustic silver, nitrate of silver, lunar caustic.
 Caustic surface Optics, a surface to which rays reflected or refracted by another surface are tangents. Caustic curves and surfaces are called catacaustic when formed by reflection, and diacaustic when formed by refraction.
 Syn: -- Stinging; cutting; pungent; searching.

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