/ Dictionary / Index C caustic surface: Meaning and Definition of Find definitions for: caus'tic sur'face Pronunciation: [key] — Optics. Optics. the surface to which all light rays emanating from a single point and reflected by a curved surface, as a concave mirror, are tangent. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. caustic soda cauterant Related Content Daily Word Quiz: abstain Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language