permafrost

American  

[pur-muh-frawst, -frost] / ˈpɜr məˌfrɔst, -ˌfrɒst /

noun

1. (in Arctic or subarctic regions) perennially frozen subsoil.

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permafrost British  

/ ˈpɜːməˌfrɒst /

noun

1. ground that is permanently frozen, often to great depths, the surface sometimes thawing in the summer

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permafrost Scientific  

/ pûr′mə-frôst′ /

1. A layer of soil or bedrock that has been continuously frozen for at least two years and as long as tens of thousands of years. Permafrost can reach depths of up to 1,524 m (4,999 ft). It is found throughout most of the polar regions and underlies about one fifth of the Earth's land surface.

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Etymology

Origin of permafrost

First recorded in 1943; perma(nent) + frost

Explanation

Permafrost is ground that is frozen permanently. As you can imagine, permafrost is extremely cold. If you know that frost has many cold-related meanings and permanent means "always," then you should be able to figure out what permafrost is: ground that is permanently frozen. You won't be able to plant a garden in permafrost — or do much with it — since it’s so hard and cold. You won't find permafrost in warm climates or places that have distinct seasons. Permafrost only exists in areas where it's cold all the time, so the ground never thaws out.

Example Sentences

See Examples For:

permafrost

"In some catchments where permafrost has become patchier, weathering-driven carbon uptake was large enough to offset or even exceed river CO2 emissions."

From Science Daily ● Jun. 20, 2026

They analyzed river CO2 emissions, dissolved carbon, isotopic tracers, and geochemical models to better understand how thawing permafrost affects carbon cycling.

From Science Daily ● Jun. 20, 2026

Areas with continuous permafrost showed only modest offsets.

From Science Daily ● Jun. 20, 2026

Shortly afterward, lawmakers amended the country's glacier protection law to relax restrictions on mining in areas of permafrost, despite fears the new law could endanger crucial water supplies.

From Barron's ● May 23, 2026

It was as if the earth itself, the permafrost, were slowly awakening from a long dream of being frozen.

From "The Subtle Knife" by Philip Pullman