/ Dictionary / Index L light pen: Meaning and Definition of Find definitions for: light' pen" Pronunciation: [key] — Computers. Computers. a hand-held light-sensitive device used for pointing at characters or objects on a CRT in order to make or modify drawings or to indicate functions to be performed. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. light opera light pipe 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