/ Dictionary / Index U underdo: Meaning and Definition of Find definitions for: un•der•do Pronunciation: (un"dur-d'), [key] — -did, -done, -do•ing. to do less or in a lesser fashion than is usual or requisite. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. underdeveloped underdog Related Content Daily Word Quiz: fabricate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language