the maximum depth at which soil is frozen.
the lower limit of permafrost.
Compare permafrost table.
Origin of frostline
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
the deepest point in the ground to which frost will penetrate
the limit towards the equator beyond which frosts do not occur
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
In regions where there is no permafrost, the maximum depth to which frost penetrates the ground in the winter.
The lower limit of permafrost.
In tropical regions, the elevation below which frost never occurs.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.