What is "kilowatt hour"

Kilowatt hour \Kil"o*watt` hour\ (Elec.) A unit of work or energy equal to that done by one kilowatt acting for one hour; -- approximately equal to 1.34 horse-power hour.

n. a unit of energy equal to the work done by a power of 1000 watts operating for one hour [syn: kW-hr, Board of Trade unit, B.T.U.]

The kilowatt hour (symbol kWh, kW·h, or kW h) is a derived unit of energy equal to 3.6 megajoules.

Thompson, Ambler and Taylor, Barry N. (2008). Guide for the Use of the International System of Units (SI) (Special publication 811). Gaithersburg, MD: National Institute of Standards and Technology. 12.

"Half-high dots or spaces are used to express a derived unit formed from two or more other units by multiplication."
Barry N. Taylor. (2001 ed.) The International System of Units.
(Special publication 330). Gaithersburg, MD: National
Institute of Standards and Technology. 20.

If the energy is being transmitted or used at a constant rate (power) over a period of time, the total energy in kilowatt-hours is the product of the power in kilo watts and the time in hours. The kilowatt-hour is commonly used as a billing unit for energy delivered to consumers by electric utilities.