Pronunciation: (plī'u-sēn"), [key] Geol.
noting or pertaining to an epoch of the Tertiary Period, occurring from 10 to 2 million years ago, and characterized by increased size and numbers of mammals, by the growth of mountains, and by global climatic cooling. See table under geologic time.
the Pliocene Epoch or Series.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.