geothermal

American  

[jee-oh-thur-muhl] / ˌdʒi oʊˈθɜr məl /

Or geothermic

adjective

1. of or relating to the internal heat of the earth.

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geothermal British  

/ ˌdʒiːəʊˈθɜːməl /

adjective

1. of or relating to the heat in the interior of the earth

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geothermal Scientific  

/ jē′ō-thûr′məl /

1. Relating to the internal heat of the Earth. The water of hot springs and geysers is heated by geothermal sources.

2. ◆ Geothermal energy is power generated from natural steam, hot water, hot rocks, or lava in the Earth's crust. In general, geothermal power is produced by pumping water into cracks in the Earth's crust and then conveying the heated water or steam back to the surface so that its heat can be extracted through a heat exchanger, or its pressure can be used to drive turbines.

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Etymology

Origin of geothermal

First recorded in 1870–75; geo- + thermal

Explanation

Heat that rises from the center of the earth is geothermal. If you ever have the chance to dip your toes in a natural hot spring, you can feel that geothermal warmth for yourself! Anything that's thermal has to do with heat, from the Greek therme. The prefix geo-, or "earth," makes it clear that this type of heat rises from the planet itself. Hot springs are warmed by geothermal energy. Geothermal energy is also a renewable source of heat and power. Many buildings use geothermal heating and it's also a good way to generate electricity.

Example Sentences

Fervo, a geothermal startup that made its public debut last week, is closer than many to fulfilling that promise.

From The Wall Street Journal • May 26, 2026

To test the system, researchers used synthetic brines designed to mimic conditions at California's Salton Sea, a geothermal region believed to contain enough lithium to supply more than 375 million EV batteries.

From Science Daily • May 23, 2026

A lack of available fuel and the rise of faster, cheaper alternatives like solar power, gas, or geothermal energy could derail the stock, Jefferies points out.

From Barron's • May 19, 2026

The Imperial Valley is a key interconnection point for regional solar, geothermal and battery storage projects.

From Los Angeles Times • May 17, 2026

At the center of the camp, water from a geothermal well had been piped into a pair of shallow, steaming pools lined with rocks and shaded by palm trees: Oh-My-God Hot Springs.

From "Into the Wild" by Jon Krakauer