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1. A unit of heat equal to the amount of heat required to raise one pound of water one degree Fahrenheit at one atmosphere pressure; equivalent to 251.997 calories
   - British thermal unit, B.Th.U.

1. A unit of energy equal to the work done by a power of 1000 watts operating for one hour
   - kilowatt hour, kW-hr, Board of Trade unit [UK], kWh

Derived forms: BTUs

Type of: energy unit, heat unit, work unit

Part of: therm

Encyclopedia: BTU