/ Dictionary / Index D defoliant: Meaning and Definition of Find definitions for: de•fo•li•ant Pronunciation: (dē-fō'lē-unt), [key] — n. a preparation for defoliating plants. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: defoliant (Thesaurus) defogger defoliate Related Content Daily Word Quiz: supercilious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language