/ Dictionary / Index O optical maser: Meaning and Definition of Find definitions for: op'tical ma'ser Pronunciation: [key] — Physics. Physics. laser. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. optical isomerism optical path Related Content Daily Word Quiz: reluctant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language