/ Dictionary / Index L light valve: Meaning and Definition of Find definitions for: light' valve" Pronunciation: [key] — Elect. Elect. a light-transmitting device having transmissions that vary in accordance with an electric input, as voltage, current, or an electron beam, used chiefly for recording sound on motion-picture film. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. lighttight light verse Related Content Daily Word Quiz: rustic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language