[fee-noh-bahr-bi-tawl, -tal, -nuh-]

noun Pharmacology.

a white, crystalline powder, C12H12N2O3, used as a sedative, a hypnotic, and as an antispasmodic in epilepsy.

Also especially British, phe·no·bar·bi·tone [fee-noh-bahr-bi-tohn, -nuh-] /ˌfi noʊˈbɑr bɪˌtoʊn, -nə-/.

Origin of phenobarbital

First recorded in 1915–20; pheno- + barbital Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for phenobarbital

Contemporary Examples of phenobarbital

British Dictionary definitions for phenobarbital



a white crystalline derivative of barbituric acid used as a sedative for treating insomnia and as an anticonvulsant in epilepsy. Formula: C 12 H 12 N 2 O 3
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

Word Origin and History for phenobarbital

1919, from pheno- + barbital (see barbiturate).

Online Etymology Dictionary, © 2010 Douglas Harper

phenobarbital in Medicine


[fē′nō-bärbĭ-tôl′, -tăl′]


A crystalline barbiturate used as a sedative, hypnotic, and anticonvulsant.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

phenobarbital in Science


[fē′nō-bärbĭ-tôl′, -tăl′]

A crystalline barbiturate used as a sedative and an anticonvulsant. Chemical formula: C12H12N2O3.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.