eon

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noun \ ˈē-ən , ˈē-ˌän \

variants: or chiefly British aeon

Definition of eon

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

See eon defined for English-language learners

Recent Examples of eon from the Web

In other words, some of these ancient trees, growing in a forest eons before humans arrived, rivaled the redwoods in size.

— ben raines, NOLA.com, "Gulf's 60,000-year-old underwater forest spills its secrets in new documentary," 25 June 2017
In the music world that's an eon—especially for a young band with as much forward momentum and buzz as Fleet Foxes had in 2011.

— matt miller, Esquire, "The Best Songs of 2017 (So Far)," 6 June 2017
The Top 10 Most-Followed Celebrities on Instagram in 2017 Getting all our double-taps?. The year 2017 is still young, but a few months in Instagram Time can feel like eons (so many selfies, so little time).

— lori keong, Marie Claire, "The Top 10 Most-Followed Celebrities on Instagram in 2017," 18 Apr. 2017
The wilderness area is studded with these sandstone hoodoos, carved by water over the eons, as well as petrified wood and dinosaur bones.

— jackie burrell, The Mercury News, "GeoQuiz: Hoodoos, badlands — and a dinosaur hunter?," 2 Apr. 2017
For eons, men and women have searched for plants or foods that could turn on desire.

— alicia ault, Smithsonian, "Are Oysters an Aphrodisiac?," 13 Feb. 2017
How many other family trees fell during those eons, how many children died young, how many mothers didn’t survive childbirth, how many future fathers never came home from wars, shipwrecks, pogroms or posses?

— kedric francis, Orange County Register, "We are family," 1 Feb. 2017
Pluto has tilted over the eons, leaning so that the region always faces Pluto’s moon, Charon — a strong hint Sputnik Planum is heavier than surrounding areas.

— korey haynes, Discover Magazine, "Pluto’s Hidden Ocean," 19 Dec. 2016
That’s a surprise for the Archean eon, a time when Earth’s atmosphere closer to the surface seems to have been almost oxygen free.

— andrew tomkins, National Geographic, "World’s Oldest Space Pebbles Found in Australia," 11 May 2016

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'eon.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of eon

Latin, from Greek aiōn — more at ³aye

NEW! Time Traveler

First Known Use: circa 1642

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Other Geology Terms

anthracite, boulder, cwm, erratic, igneous, intrusive, mesa, sedimentary, silt, swale

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