/ Dictionary / Index O optical isomerism: Meaning and Definition of Find definitions for: op'tical isom'erism Pronunciation: [key] — Chem. Chem. stereoisomerism in which the isomers are identical in molecular weight and most chemical and physical properties but differ in their effect on the rotation of polarized light. Cf. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. optical isomer optical maser Related Content Daily Word Quiz: loathe Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language