/ Dictionary / Index L long underwear: Meaning and Definition of Find definitions for: long' un'derwear Pronunciation: [key] a close-fitting, usually knitted undergarment with legs reaching to the ankles, as a union suit, worn as protection against the cold. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. longueur long vacation Related Content Daily Word Quiz: hedonist Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language