: of, relating to, or utilizing the heat of the earth's interior
also : produced or permeated by such heat
geothermal steam
geothermal regions

Did you know?

Geothermal comes partly from the Greek thermos, "hot". Most geothermal electricity is provided by power plants situated in areas where there is significant activity of the Earth's great tectonic plates—often the same areas where volcanoes are found. But hot water from deep underground may be used by cities far from volcanoes to heat buildings or sidewalks. And a newer source of geothermal energy relies on a less dramatic kind of heat: Individual homeowners can now install heat pumps that take advantage of the 50°-60° temperature of the soil near the surface to provide heating in cold weather (and air-conditioning in the warm months). These very small-scale geothermal systems may eventually supply more useful energy than the large power plants.

Examples of geothermal in a Sentence

Recent Examples on the Web
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Fittingly, the hotel takes great care to disrupt its surroundings as little as possible; a geothermal well services the property’s heating and cooling, and plants that draw mosquito-eating birds are used in place of pesticides. — Condé Nast, Condé Nast Traveler, 31 Oct. 2026 Meanwhile, Microsoft and Google are signing long-term deals for nuclear and geothermal power. — Jake Rozmaryn, Fortune, 28 Oct. 2026 Micron’s money will back a $1 million grant from Bloomberg Philanthropies to the city to pilot geothermal heating, which would make the Lusk block the first affordable multifamily complex in the nation to utilize geothermal. — Mark Dee october 27, Idaho Statesman, 27 Oct. 2026 Powered by renewable electricity, from local resources like the solar panels on Lovins’ roof and mine, or from larger solar, wind and geothermal facilities, these technologies can slash fossil fuel use. — Daniel Cohan, The Conversation, 26 Oct. 2026 See All Example Sentences for geothermal

Word History

Etymology

geo- + thermal entry 1

First Known Use

1875, in the meaning defined above

Time Traveler
The first known use of geothermal was in 1875

Browse Nearby Words

Cite this Entry

“Geothermal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/geothermal. Accessed 9 Nov. 2026.

Kids Definition

geothermal

adjective
variants also geothermic
-mik
: of, relating to, or using the heat of the earth's interior
also : produced by such heat
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