eon

noun \ ˈē-ən , ˈē-ˌän \

variants: or chiefly British aeon

Updated on: 17 Apr 2018

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 that sense, the game felt eons away from where this program was a year ago.

— shawn windsor, Detroit Free Press, "Michigan State football eons away from where it was in 2017," 7 Apr. 2018
Horn-faced dinosaurs like Triceratops had elaborate frills and spurs that adorned their skulls and grew more elaborate—and diverse—through the eons.

— gretchen vogel, Science | AAAS, "What made Triceratops so horny?," 20 Mar. 2018
In addition to searching the galaxy for life, the GMT will allow astronomers to study the most ancient eons of the universe, probing the firmament to test our fundamental laws of physics.

— jay bennett, Popular Mechanics, "The Deep Space Eye in the Desert," 14 Feb. 2018
Are these 80-odd tools, eons more ancient than the ancient world, indeed art works?

— jason farago, New York Times, "Was Australopithecus an Artist?," 1 Feb. 2018
The idea is that volcanic eruptions released lava that found their way into underground coal deposits built up over previous eons and ignited them.

— avery thompson, Popular Mechanics, "The World's Largest Mass Extinction May Have Been Caused by Burning Coal," 13 Mar. 2018
The year 2018 is still young, but a couple months in Instagram Time can feel like eons (so many selfies, so little time).

— rachel epstein, Marie Claire, "The Top 10 Most-Followed Celebrities on Instagram in 2018," 21 Feb. 2018
If on the other hand, some previously unsuspected force field is tinkering with the galaxies and space-time, the effect could shut off or even reverse over the eons.

— dennis overbye, New York Times, "Astronomers’ Dark Energy Hopes Fade to Gray," 19 Feb. 2018
Stretching back across the eons, conservatives have been asking for more consideration at the New York Times, which is still the most influential news outlet in the United States.

— kyle smith, National Review, "In Praise of the New York Times Opinion Section. No, Really.," 16 Feb. 2018

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

in the meaning defined at sense 1

See Words from the same year

Other Geology Terms

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

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