/ Dictionary / Index L Luminal: Meaning and Definition of Find definitions for: Lu•mi•nal Pronunciation: (l'mu-nl), [key] — Pharm., Trademark. Pharm.,Trademark. a brand of phenobarbital. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: luminal (Thesaurus) Luminaire luminance Related Content Daily Word Quiz: pundit Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language