therm vs British thermal unit

therm and British thermal unit both are nouns.

Word	Noun	Adjective	Verb	Adverb
therm	Yes	No	No	No
British thermal unit	Yes	No	No	No

therm (noun)	British thermal unit (noun)
a unit of heat equal to 100,000 British thermal units	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