/ Dictionary / Index M MDMA: Meaning and Definition of Find definitions for: MDMA Pronunciation: [key] methylene dioxymethamphetamine: an amphetamine derivative, CHNO, that reduces inhibitions and that was used in psychotherapy until it was banned in the U.S. in 1985. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: mdma (Thesaurus) Mdm. Mdme. Related Content Daily Word Quiz: eureka Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language