British thermal unit

noun

: the quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit at a specified temperature (such as 39°F)

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Despite its name, the British thermal unit, or BTU, may be more widely used in North America than in Britain. Air conditioners, furnaces, and stoves are generally rated by BTUs. (Though "BTUs" is often short for "BTUs per hour;" in air-conditioner ratings, for instance, "BTUs" really means "BTUs of cooling capacity per hour".) Fuels such as natural gas and propane are also compared using BTUs. The BTU first appeared in 1865 and isn't part of the metric system—the metric unit of energy is the much smaller joule—so it isn't much used by scientists, but its practicality keeps it popular for consumer goods and fuels. A better-known heat unit is the calorie; a BTU is equal to about 252 calories. (Since the familiar food calorie is actually a kilocalorie, a BTU equals only about a quarter of a food calorie.)

Examples of British thermal unit in a Sentence

Recent Examples on the Web
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Benchmark Henry Hub natural gas reached $3.66 per million British thermal units on Thursday, peaking at $4.20 earlier in the week. Amanda Castro, Newsweek, 3 Jan. 2025 One British thermal unit is equivalent to 1,055 joules and will raise the temperature of one pound of water one degree Fahrenheit. Matthew J. C. Clark, Harper's Magazine, 2 Aug. 2024 The price of natural gas surged more than 15% early Monday, nearing $4 per million British thermal units. Jeff Marks, CNBC, 30 Dec. 2024 The Henry Hub natural gas spot price averaged $2.15 per million British thermal units (MMBtu) through December 16, falling short of 2023's $2.53/MMBtu average. Robert Rapier, Forbes, 27 Dec. 2024 Analysts now predict that LNG prices in Asia could soar to over $20 per million British thermal units (mmBtu) if global supply tightens. Dan Eberhart, Forbes, 12 Dec. 2024 The summer and fall have also been volatile — but in the past month, natural gas is up a little over 12% and traded just over $3 per million British thermal units on Friday. Kevin Stankiewicz, CNBC, 6 Dec. 2024 There’s lots of room for more buybacks and payout hikes, as CF’s sales and earnings gained in the third quarter, with profits getting an assist from a drop in the price of natural gas, CF’s main feedstock, from $2.58 per million British thermal units a year ago to $2.08. Brett Owens, Forbes, 6 Nov. 2024 For example, the Maryland Bioenergy Center is capable of processing up to 110,000 tons of food waste annually, producing 312 billion British thermal units of renewable natural gas and more than 15,000 tons of fertilizer, the Agriculture Dive piece said. Sergey Buchin, Forbes, 23 Oct. 2024

Word History

First Known Use

1865, in the meaning defined above

Time Traveler
The first known use of British thermal unit was in 1865

Dictionary Entries Near British thermal unit

Cite this Entry

“British thermal unit.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/British%20thermal%20unit. Accessed 18 Jan. 2025.

Kids Definition

British thermal unit

noun
: the quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit at a specified temperature (as 39°F or 60°F) and equal to about 1055 joules
called also Btu

Medical Definition

British thermal unit

noun
: the quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit at a specified temperature (as 39°F)
abbreviation Btu

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