permafrost

[ pur-muh-frawst, -frost ]

/ ˈpɜr məˌfrɔst, -ˌfrɒst /

SEE MORE SYNONYMS FOR permafrost ON THESAURUS.COM

noun

(in arctic or subarctic regions) perennially frozen subsoil.

Nearby words

perma-, perma-press, perma-tan, permaculture, permadeath, permafrost, permafrost table, permalink, permalloy, permanence, permanency

Origin of permafrost

First recorded in 1943; perma(nent) + frost

Also called pergelisol.

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for permafrost

I wondered what would happen to the trees if some of the permafrost melted, allowing roots to expand in longer growing seasons.
Visiting the Arctic Circle…Before It’s Irreversibly Changed|Terry Greene Sterling|April 1, 2014|DAILY BEAST

British Dictionary definitions for permafrost

permafrost

/ (ˈpɜːməˌfrɒst) /

noun

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

Word Origin for permafrost

C20: from perma (nent) + frost

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Science definitions for permafrost

permafrost

[ pûr′mə-frôst′ ]

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.