/ Dictionary / Index E endorphin: Meaning and Definition of Find definitions for: en•dor•phin Pronunciation: (en-dôr'fin), [key] — n. any of a group of peptides occurring in the brain and other tissues of vertebrates, and resembling opiates, that react with the brain's opiate receptors to raise the pain threshold. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: endorphin (Thesaurus) endorheic endorsation Related Content Daily Word Quiz: penchant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language