/ Dictionary / Index U underwaist: Meaning and Definition of Find definitions for: un•der•waist Pronunciation: (un'dur-wāst"), [key] — n. a blouse worn under another. such a blouse to which other undergarments are pinned or buttoned, worn by infants and small children. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. undervest underwater Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language