epoch

American  

[ep-uhk, ee-pok] / ˈɛp ək, ˈi pɒk /

noun

• epochs
  plural

1. a particular period of time marked by distinctive features, events, etc..

   The treaty ushered in an epoch of peace and good will.

   Synonyms:

   time, era, date, age

2. the beginning of a distinctive period in the history of anything.

   The splitting of the atom marked an epoch in scientific discovery.

3. 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.

4. Geology. any of several divisions of a geologic period during which a geologic series is formed.

5. Astronomy.

   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.

6. Physics. the displacement from zero at zero time of a body undergoing simple harmonic motion.

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epoch British  

/ ˈiːpɒk, ˈɛpˌɒkəl /

noun

1. a point in time beginning a new or distinctive period

   the invention of nuclear weapons marked an epoch in the history of warfare

2. a long period of time marked by some predominant or typical characteristic; era

3. astronomy a precise date to which information, such as coordinates, relating to a celestial body is referred

4. geology a unit of geological time within a period during which a series of rocks is formed

   the Pleistocene epoch

5. physics the displacement of an oscillating or vibrating body at zero time

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epoch Scientific  

/ ĕp′ək,ē′pŏk′ /

1. The shortest division of geologic time. An epoch is a subdivision of a period.

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Synonym Usage

See age.

Other Word Forms

Derived Forms

• subepoch
  noun
• superepoch
  noun
• epochal
  adjective
• epochally
  adverb

Inflected Forms

Nouns

• epochs
  plural

Etymology

Origin of epoch

First recorded in 1605–15; from New Latin epocha, from Greek epochḗ “pause, check, fixed time,” from ep- ep- + och- (variant stem of échein “to have, hold, keep”) + -ē, noun suffix

Explanation

An epoch is a period of time marked by certain characteristics: You might describe several peaceful decades in a nation's history as an epoch of peace. In geologic time, an epoch is a division of a period, and an age is a division of an epoch. Epoch can also refer to a distinct and important period of history, or an event that marks such a period: an epoch in the world of ballet, for example. The noun epoch is from New Latin epocha, from Greek epochē, "pause, check, fixed time."

Example Sentences

See Examples For:

epoch epochs

The Eocene epoch, which lasted from roughly 56 to 34 million years ago, provides a clear example of what happened when the carbon burial feedback was largely inactive.

From Science Daily ● Jul. 16, 2026

The same bounty that makes the Tar Pits the best place on Earth to study its slice of the late Pleistocene epoch also makes for a move of truly mammoth proportions.

From Los Angeles Times ● Jun. 6, 2026

So how should investors position themselves for this new, problematic epoch?

From MarketWatch ● Apr. 10, 2026

I've been presenting television debates and radio phone-ins over five decades, stumbling from one epoch to the next.

From BBC ● Mar. 7, 2026

By looking far out into space we are also looking far back into time, back toward the horizon of the universe, back toward the epoch of the Big Bang.

From "Cosmos" by Carl Sagan

Our critic raved that “it’s an unparalleled opportunity to do a deep dive into one of the most dazzling epochs in the history of art.”

From The Wall Street Journal ● Mar. 22, 2026

Disney Chairman James Gorman said in an interview that Iger’s nearly 20 years in power is framed by two epochs: “Bob 1” and “Bob 2.”

From Los Angeles Times ● Feb. 4, 2026

"The low metallicity environment, meaning the reduced abundance of elements heavier than hydrogen and helium, is interesting because it's similar to galaxies at earlier cosmological epochs," Sewilo explained.

From Science Daily ● Nov. 12, 2025

He said Traoré was "offering an alternative, and re-capturing the spirit of two historic epochs":

From BBC ● May 11, 2025

Also, all this changes from textbook to textbook and from person to person, so that some authorities describe seven recent epochs, while others are content with four.

From "A Short History of Nearly Everything" by Bill Bryson