/ Dictionary / Index O optical astronomy: Meaning and Definition of Find definitions for: op'tical astron'omy Pronunciation: [key] the branch of observational astronomy using telescopes to observe or photograph celestial objects in visible light. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. optical art optical bench Related Content Daily Word Quiz: arboreal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language