CAUSTICAL

Adjective

caustical (comparative more caustical, superlative most caustical)

Archaic form of caustic.

Source: Wiktionary

Caus"tic, Caus"tic*al, a. Etym: [L. caustucs, Ge. Calm, Ink.]

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.

Source: Webster’s Unabridged Dictionary 1913 Edition