or watt·hour

[ wot-ouuh r, -ou-er ]
/ ˈwɒtˌaʊər, -ˌaʊ ər /


a unit of energy equal to the energy of one watt operating for one hour, equivalent to 3600 joules. Abbreviation: Wh

Origin of watt-hour

First recorded in 1885–90
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for watt-hour

  • A watt-hour is the amount of energy needed by a device which uses one watt and is operated for one hour.

  • Electricity is usually purchased by the kilowatt hour, and measured by the watt-hour meter (Fig. 160).

British Dictionary definitions for watt-hour



a unit of energy equal to a power of one watt operating for one hour. 1 watt-hour equals 3600 joules
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

Science definitions for watt-hour


A unit of energy, especially electrical energy, equal to the work done by one watt acting for one hour. It is equivalent to 3,600 joules.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.