noun Date: 1876 the quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit at a specified temperature (as 39°F)
BRITISH THERMAL UNIT
Meaning of BRITISH THERMAL UNIT in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012