1. Also called gla'cial pe"riod, ice age. the geologically recent Pleistocene Epoch, during which much of the Northern Hemisphere was covered by great ice sheets.
2. any one of the Permian, Carboniferous, Cambrian, or Precambrian glaciations.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.