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

Example Sentences

It stretches northward into desolate permafrost regions flush with “oil sands” that produce about nine times as much crude as Alaska.

From The Wall Street Journal • Feb. 14, 2026

"We gained access to exceptionally well-preserved mammoth tissues unearthed from the Siberian permafrost, which we hoped would still contain RNA molecules frozen in time," adds Emilio Mármol.

From Science Daily • Nov. 15, 2025

Canada and Russia, where large amounts of ice and permafrost are melting, are losing the most fresh water.

From Los Angeles Times • Sep. 3, 2025

Should global warming cause the thick Arctic permafrost to thaw, the vault is still robust enough to preserve its contents he says.

From BBC • May 8, 2025

At last he found what he wanted: a firm rock deep-anchored in the permafrost He backed against it, tensing his legs and choosing his moment.

From "The Golden Compass" by Philip Pullman