/ Dictionary / Index O optical sound: Meaning and Definition of Find definitions for: op'tical sound' Pronunciation: [key] — Motion Pictures. Motion Pictures. sound recorded on and subsequently played back from an optical or photographic soundtrack, as opposed to a magnetic soundtrack. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. optical scanning optical soundtrack Related Content Daily Word Quiz: jugular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language