variants or chiefly British aeon
1
: an immeasurably or indefinitely long period of time : age
I haven't seen him in eons.
2
a
: a very large division of geologic time usually longer than an era
the Archean eon
b
: a unit of geologic time equal to one billion years

Examples of eon in a Sentence

Recent Examples on the Web This union lasted yet another decade, from 1979 to 1988, a second eon in rock marriages. Guy Martin, Forbes, 28 Feb. 2024 Finding molecular water on Iris and Massalia, in particular, suggests liquid water can exist for eons on space rocks in the inner solar system—contrary to previous assumptions that any water would have evaporated from these asteroids under the heat of the sun. Catherine Duncan, Smithsonian Magazine, 16 Feb. 2024 Over eons, successive generations of stars were formed from the ashes of previous stars, enriching the chemistry of the cosmos. Dennis Overbye, New York Times, 24 Dec. 2023 There is still warmth deep within, leftover from the world’s formation eons ago, and as that heat slowly escapes to space, the planet’s crust cools, contracts and quivers. Jonathan O'Callaghan, Scientific American, 17 Oct. 2023 But a debate rages as to whether those eons can truly stretch out to eternity, as many physicists have believed. Charlie Wood, Quanta Magazine, 26 Feb. 2024 Up above the world so high, these objects—light-years away and eons old—remind us to appreciate nature whenever possible. Tracy Scott Forson, Smithsonian Magazine, 19 Jan. 2024 Obviously, inducements have been integral to the recruiting process for eons. Jon Wilner, The Mercury News, 28 Feb. 2024 Such patterns can indeed last for eons, as the breakthrough experiments found. Charlie Wood, Quanta Magazine, 26 Feb. 2024

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

Word History

Etymology

borrowed from Late Latin aeōn "age (in the world's history), evil spirit (in Gnosticism)," borrowed from Greek aiṓn "lifetime, long period of time, age" — more at aye entry 3

First Known Use

circa 1642, in the meaning defined at sense 1

Time Traveler
The first known use of eon was circa 1642

Dictionary Entries Near eon

Cite this Entry

“Eon.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/eon. Accessed 28 Mar. 2024.

Kids Definition

eon

noun
ˈē-ən
1
: a very long period of time
2
a
: a very large division of geologic time usually longer than an era
b
: a unit of geologic time equal to one billion years

More from Merriam-Webster on eon

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