- (in arctic or subarctic regions) perennially frozen subsoil.
Origin of permafrost
Also called pergelisol.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
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
- ground that is permanently frozen, often to great depths, the surface sometimes thawing in the summer
C20: from perma (nent) + frost
Word Origin and History for permafrost
1943, coined in English by Russian-born U.S. geologist Siemon W. Muller (1900-1970) from perm(anent) frost.
Online Etymology Dictionary, © 2010 Douglas Harper
- 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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.