/ Dictionary / Index O optical rotation: Meaning and Definition of Find definitions for: op'tical rota'tion Pronunciation: [key] — Physical Chem. Physical Chem. the angle at which the plane of polarized light is rotated when passed through an optically active substance. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. optical pumping optical scanning Related Content Daily Word Quiz: hale Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language