/ Dictionary / Index M MDA: Meaning and Definition of Find definitions for: MDA Pronunciation: [key] methylene dioxyamphetamine: an amphetamine derivative, CHNO, having hallucinogenic and stimulant properties. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. MD MDAP Related Content Daily Word Quiz: tenacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language