/ Dictionary / Index D diphenylhydantoin: Meaning and Definition of Find definitions for: di•phen•yl•hy•dan•to•in Pronunciation: (dī-fen'l-hī-dan'tō-in, -fēn'-), [key] — n. Pharm. a white, slightly water-soluble powder, CHNO, used in the form of its sodium salt to prevent or arrest convulsions in epilepsy. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: diphenylhydantoin (Thesaurus) diphenylaminechlorarsine diphenyl ketone Related Content Daily Word Quiz: perspicacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language