[ ep-uhk or, esp. British, ee-pok ]
/ ˈɛp ək or, esp. British, ˈi pɒk /


a particular period of time marked by distinctive features, events, etc.: The treaty ushered in an epoch of peace and good will.
the beginning of a distinctive period in the history of anything: The splitting of the atom marked an epoch in scientific discovery.
a point of time distinguished by a particular event or state of affairs; a memorable date: His coming of age was an epoch in his life.
Geology. any of several divisions of a geologic period during which a geologic series is formed.Compare age(def 12).
  1. an arbitrarily fixed instant of time or date, usually the beginning of a century or half century, used as a reference in giving the elements of a planetary orbit or the like.
  2. the mean longitude of a planet as seen from the sun at such an instant or date.
Physics. the displacement from zero at zero time of a body undergoing simple harmonic motion.

Origin of epoch

1605–15; < New Latin epocha < Greek epochḗ pause, check, fixed time, equivalent to ep- ep- + och- (variant stem of échein to have) + noun suffix

Related forms

sub·ep·och, nounsu·per·ep·och, noun

Can be confused

epic epoch

Synonym study

1. See age.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for epoch

British Dictionary definitions for epoch


/ (ˈiːpɒk) /


a point in time beginning a new or distinctive periodthe invention of nuclear weapons marked an epoch in the history of warfare
a long period of time marked by some predominant or typical characteristic; era
astronomy a precise date to which information, such as coordinates, relating to a celestial body is referred
geology a unit of geological time within a period during which a series of rocks is formedthe Pleistocene epoch
physics the displacement of an oscillating or vibrating body at zero time

Derived Forms

epochal (ˈɛpˌɒkəl), adjectiveepochally, adverb

Word Origin for epoch

C17: from New Latin epocha, from Greek epokhē cessation; related to ekhein to hold, have
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 epoch


[ ĕpək, ēpŏk′ ]

The shortest division of geologic time. An epoch is a subdivision of a period.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.