/ Dictionary / Index P Pliocene: Meaning and Definition of Find definitions for: Pli•o•cene Pronunciation: (plī'u-sēn"), [key] — Geol. Geol. —adj. 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 —n. the Pliocene Epoch or Series. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: pliocene (Thesaurus) plio- Pliofilm Related Content Daily Word Quiz: frugal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language