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

Those who think history is by its nature a sort of settled permafrost will be surprised to see how the discipline has changed over the past half century.

From The Wall Street Journal

These RNA sequences are the oldest ever recovered and come from mammoth tissue preserved in the Siberian permafrost for nearly 40,000 years.

From Science Daily

The tundra had once been covered in a permanent layer of hard frozen soil, called permafrost.

From Literature

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

From Los Angeles Times

"The thawing of permafrost at very high elevation led to the collapse of the summit," he explains.

From BBC