ep·​och ˈe-pək How to pronounce epoch (audio)
US also and British usually
ˈē-ˌpäk How to pronounce epoch (audio)
: an event or a time marked by an event that begins a new period or development
: a memorable event or date
: an extended period of time usually characterized by a distinctive development or by a memorable series of events
: a division of geologic time less than a period and greater than an age
: 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.

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 Completely ignored was the most potent enemy of New England’s historic walls in that epoch and ours: weedy vegetation. Robert Thorson, Smithsonian Magazine, 14 Nov. 2023 The last sabretooth cats went extinct in the late Pliocene period in Europe but continued roaming the planet in North and South America until the end of the Pleistocene epoch. Elizabeth Gamillo, Discover Magazine, 24 July 2023 Chess grandmasters have, in various epochs, played all the way through to the checkmate, rather than ending the game when an opponent resigns early to save face. WIRED, 26 Sep. 2023 Now China has reached the same epoch of automotive evolution—but is doing so electrically. Mike Duff, Car and Driver, 18 Aug. 2023 Not everyone is convinced that this evidence is enough to warrant designating a whole new epoch. Devika Rao, The Week, 13 July 2023 Researchers divide the Earth’s geologic history into units approved by the International Commission on Stratigraphy called eons, eras, periods, epochs and ages. Margaret Osborne, Smithsonian Magazine, 13 July 2023 That would take us back to the previous geologic epoch, the Pliocene, when the Earth’s climate was a distant relative of the one that sustained the rise of agriculture and civilization. Darrell Kaufman, Fortune, 23 July 2023 The most famous extinction event in the planet’s history is happening again — in Santa Cruz May 31, 2023 Geologists measure time in eons, eras, periods, epochs and ages. Seth Borenstein, Los Angeles Times, 11 July 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'epoch.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


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

Time Traveler
The first known use of epoch was in 1614


Dictionary Entries Near epoch

Cite this Entry

“Epoch.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/epoch. Accessed 4 Dec. 2023.

Kids Definition


ep·​och ˈep-ək How to pronounce epoch (audio) -ˌäk How to pronounce epoch (audio)
 also  ˈē-ˌpäk
: an event or a time that begins a new period of development
: a memorable event, date, or period
: a division of geologic time less than a period and greater than an age

More from Merriam-Webster on epoch

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