/ Dictionary / Index M mercaptopurine: Meaning and Definition of Find definitions for: mer•cap•to•pu•rine Pronunciation: (mur-kap"tō-pyoor'ēn), [key] — n. Pharm. a yellow, crystalline, water-insoluble powder, CHNS, used in the treatment of leukemia. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: mercaptopurine (Thesaurus) mercapto group Mercast Related Content Daily Word Quiz: panacea Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language