[ pur-muh-frawst, -frost ]
/ ˈpɜr məˌfrɔst, -ˌfrɒst /
(in arctic or subarctic regions) perennially frozen subsoil.
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
/ (ˈpɜːməˌfrɒst) /
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
[ 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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.