/ Dictionary / Index P Pleistocene: Meaning and Definition of Find definitions for: Pleis•to•cene Pronunciation: (plī'stu-sēn"), [key] — Geol. Geol. —adj. noting or pertaining to the epoch forming the earlier half of the Quaternary Period, beginning about two million years ago and ending 10,000 years ago, characterized by widespread glacial ice and the advent of modern humans. See table under —n. the Pleistocene Epoch or Series. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: pleistocene (Thesaurus) pleiotropy Plekhanov Related Content Daily Word Quiz: gregarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language