/ Dictionary / Index N naltrexone: Meaning and Definition of Find definitions for: nal•trex•one Pronunciation: (nal-trek'sōn), [key] — n. Pharm. a nonaddictive substance, CHNO, used in the treatment of heroin addiction and opiate overdose. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: naltrexone (Thesaurus) naloxone Nam Related Content Daily Word Quiz: banshee Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language