[ fen-i-toh-in, fuh-nit-oh- ]
/ ˌfɛn ɪˈtoʊ ɪn, fəˈnɪt oʊ- /

noun Pharmacology.

a barbiturate-related substance, C15H12N2O2, used as an anticonvulsant in the treatment of grand mal epilepsy and in focal seizures.

Origin of phenytoin

1940–45; (di)pheny(lhydan)toin, its full chemical name; see di-1, phenyl, hydantoin Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for phenytoin


/ (ˌfɛnɪˈtəʊɪn) /


an anticonvulsant drug used in the management of epilepsy and in the treatment of abnormal heart rhythms. Formula: C 15 H 11 N 2 O 2 NaAlso called: diphenylhydantoin sodium

Word Origin for phenytoin

C20: from (di) pheny (lhydan) toin
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medicine definitions for phenytoin


[ fĕn′ĭ-tōĭn, fə-nĭtō- ]


An anticonvulsant drug chemically related to the barbiturates and used most commonly in the treatment of epilepsy.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.