a unit of heat in the fps system equal to the quantity of heat required to raise the temperature of 1 pound of water by 1°F. 1 British thermal unit is equivalent to 1055.06 joules or 251.997 calories
Abbrevs: btu, BThU
BTU in British English
abbreviation for
Board of Trade Unit
Board of Trade Unit in British English
noun
a unit of electrical energy equal to 1 kilowatt-hour