/ Dictionary / Index A achromatic prism: Meaning and Definition of Find definitions for: ach'romat'ic prism' Pronunciation: [key] — Optics. Optics. a system of two or more prisms of different substances that deflects but does not disperse a beam of light. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. achromatic lens achromatism Related Content Daily Word Quiz: jaundice Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language