/ Dictionary / Index M Miocene: Meaning and Definition of Find definitions for: Mi•o•cene Pronunciation: (mī'u-sēn"), [key] — Geol. Geol. —adj. noting or pertaining to an epoch of the Tertiary Period, occurring from 25 to 10 million years ago, when grazing mammals became widespread. See table under —n. the Miocene Epoch or Series. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: miocene (Thesaurus) Minyas miosis Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language