epoch

noun

ep·​och ˈe-pək 

ˈe-ˌpäk,

US also and British usually

ˈē-ˌpäk 

1

a

: an event or a time marked by an event that begins a new period or development

b

: a memorable event or date

2

a

: an extended period of time usually characterized by a distinctive development or by a memorable series of events

b

: a division of geologic time less than a period and greater than an age

3

: an instant of time or a date selected as a point of reference (as in astronomy)

Did you know?

Epoch comes to us, via Medieval Latin, from Greek epochē, meaning "cessation" or "fixed point." "Epochē," in turn, comes from the Greek verb epechein, meaning "to pause" or "to hold back." When "epoch" was first borrowed into English, it referred to the fixed point used to mark the beginning of a system of chronology. That sense is now obsolete, but today "epoch" is used in some fields (such as astronomy) with the meaning "an instant of time or a date selected as a point of reference." The "an event or a time that begins a new period or development" sense first appeared in print in the early 17th century, and "epoch" has been applied to defining moments or periods of time ever since.

Synonyms

• era
• day
• time
• period
• age

Choose the Right Synonym for epoch

period, epoch, era, age mean a division of time.

period may designate an extent of time of any length.

periods of economic prosperity

epoch applies to a period begun or set off by some significant or striking quality, change, or series of events.

the steam engine marked a new epoch in industry

era suggests a period of history marked by a new or distinct order of things.

the era of global communications

age is used frequently of a fairly definite period dominated by a prominent figure or feature.

the age of Samuel Johnson

Examples of epoch in a Sentence

The Civil War era was an epoch in 19th-century U.S. history.

The development of the steam engine marked an important epoch in the history of industry.

Recent Examples on the Web

With the pair at the helm, the goal was to standardize the superhero universe and kick-start a new epoch for the studio. —Los Angeles Times, 10 July 2025

For this study, a research team from University College London (UCL) looked at the impacts of two major asteroids from the late Eocene epoch (about 38 million to 33 million years ago). —Monica Cull, Discover Magazine, 10 July 2025

The Plio-Pleistocene transition marked the passage from the wetter and more humid Pliocene epoch (5.3 million years to 2.6 million years ago) to the colder and drier Pleistocene epoch (2.6 million years to 11,700 years ago). —Jack Knudson, Discover Magazine, 23 June 2025

For all that this season marks a new epoch in the tale of booming UEFA prize money, cash will be far from the thoughts of Paris Saint-Germain on Saturday evening in Munich. —Chris Weatherspoon, New York Times, 31 May 2025

Word History

Etymology

Medieval Latin epocha, from Greek epochē cessation, fixed point, from epechein to pause, hold back, from epi- + echein to hold — more at scheme entry 1

First Known Use

1614, in the meaning defined at sense 1a

Phrases Containing epoch

• epoch-making

Rhymes for epoch

• epic

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Kids Definition

epoch

noun

ep·​och ˈep-ək  -ˌäk 

 also  ˈē-ˌpäk

1

: an event or a time that begins a new period of development

2

: a memorable event, date, or period

3

: a division of geologic time less than a period and greater than an age

epochal

-əl

adjective

epochally

-ə-lē

adverb