/ Dictionary / Index R relative complement: Meaning and Definition of Find definitions for: rel'ative com'plement Pronunciation: [key] — Math. Math. the set of elements contained in a given set that are not elements of another specified set. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. relative clause relative density Related Content Daily Word Quiz: belligerent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language