/ Dictionary / Index L least common denominator: Meaning and Definition of Find definitions for: least' com'mon denom'inator Pronunciation: [key] — Math. Math. the smallest number that is a common denominator of a given set of fractions. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. least bittern least common multiple Related Content Daily Word Quiz: lunar Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language