/ Dictionary / Index L lacking: Meaning and Definition of Find definitions for: lack•ing Pronunciation: (lak'ing), [key] — prep. being without; not having; wanting; less: Lacking equipment, the laboratory couldn't undertake the research project. —adj. wanting; deficient: He was found lacking in stamina. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: lacking (Thesaurus) lackey Lackland Air Force Base Related Content Daily Word Quiz: rustic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language