/ Dictionary / Index L leavening: Meaning and Definition of Find definitions for: leav•en•ing Pronunciation: (lev'u-ning), [key] — n. a substance used to produce fermentation in dough or batter; leaven. the act or process of causing to ferment by leaven. leaven (def. 3). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: leavening (Thesaurus) leaven Leavenworth Related Content Daily Word Quiz: impetuous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language