[ ol-i-goh-seen ]
/ ˈɒl ɪ goʊˌsin /


noting or pertaining to an epoch of the Tertiary Period, occurring from 40 to 25 million years ago.


the Oligocene Epoch or Series.

Origin of Oligocene

First recorded in 1855–60; oligo- + -cene

Related forms

post-Ol·i·go·cene, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for oligocene

British Dictionary definitions for oligocene


/ (ˈɒlɪɡəʊˌsiːn, ɒˈlɪɡ-) /


of, denoting, or formed in the third epoch of the Tertiary period, which lasted for 10 000 000 years


the Oligocene the Oligocene epoch or rock series

Word Origin for Oligocene

C19: oligo- + -cene
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Science definitions for oligocene


[ ŏlĭ-gō-sēn′ ]

The third epoch of the Tertiary Period, from about 37 to 24 million years ago. During this time there was an increase in volcanic activity, and Australia and South America separated from Antarctica. The climate started to cool and a glacier started to form in Antarctica. Modern mammalian groups continued to develop, and the first cats, dogs, horses, and related mammals appeared. Artiodactyls (even-toed ungulates) took over from the perissodactyls (uneven-toed ungulates) as the dominant medium-sized herbivores. Many types of grass also first appeared at this time. See Chart at geologic time.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.