Dictionary.com

Eocene

[ ee-uh-seen ]
/ ˈi əˌsin /
Geology
Save This Word!

adjective
noting or pertaining to an epoch of the Tertiary Period, occurring from 55 to 40 million years ago and characterized by the advent of the modern mammalian orders.
noun
the Eocene Epoch or Series.
QUIZ
ARE YOU A TRUE BLUE CHAMPION OF THESE "BLUE" SYNONYMS?
We could talk until we're blue in the face about this quiz on words for the color "blue," but we think you should take the quiz and find out if you're a whiz at these colorful terms.
Question 1 of 8
Which of the following words describes “sky blue”?
Meet Grammar CoachWrite or paste your essay, email, or story into Grammar Coach and get grammar helpImprove Your Writing
Meet Grammar CoachImprove Your Writing
Write or paste your essay, email, or story into Grammar Coach and get grammar help

Origin of Eocene

First recorded in 1825–35; eo- + -cene

OTHER WORDS FROM Eocene

post-E·o·cene, adjective

Words nearby Eocene

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

How to use Eocene in a sentence

British Dictionary definitions for Eocene

Eocene
/ (ˈiːəʊˌsiːn) /

adjective
of, denoting, or formed in the second epoch of the Tertiary period, which lasted for 20 000 000 years, during which hooved mammals appeared
noun
the Eocene the Eocene epoch or rock series

Word Origin for Eocene

C19: from eo- + -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

Scientific definitions for Eocene

Eocene
[ ēə-sēn′ ]

The second epoch of the Tertiary Period, from about 58 to 37 million years ago. During the earliest part of this epoch, land connections existed between Antarctica and Australia, between Europe and North America, and between North America and Asia, and the climate was warm. The land connection between Antarctica and Australia disappeared in the mid-Eocene and early Oligocene, resulting in a change in the predominant oceanic currents and a cooler climate. With this change, the average size of mammals changed from less than 10 kg (22 lbs) to more than 10 kg. The Himalayas also formed during the Eocene, and most modern orders of mammals appeared. See Chart at geologic time.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
FEEDBACK