\ˈē-ən, ˈē-ˌän \
variants: or chiefly British

Definition of eon 

1 : an immeasurably or indefinitely long period of time : age I haven't seen him in eons.

2a : 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

The single-use plastic straw — colorful, functional and handed out in bunches — has suddenly shifted from consumer staple to scourge, projected by some critics to foul ecosystems for an eon. Robert Channick, chicagotribune.com, "From a South Side plastics factory to McDonald's HQ, Chicago is on the front lines of anti-straw push," 11 June 2018 To uncover evidence of the collision so many eons later, astronomers have to work like galactic archaeologists, sifting through myriad sources of surviving information to piece together a story consistent with the available evidence. Ramin Skibba, WIRED, "This Galactic Collision Shaped the History of the Milky Way," 8 July 2018 Valdes balanced on one leg for what felt like eons, changing positions from arabesque to passe develope without the use of her partner, Patricio Reve. Lauren Warnecke, chicagotribune.com, "Ballet Nacional de Cuba's 'Don Quixote' is unapologetically unrefreshed — and the dancing is glorious," 19 May 2018 Doesn't this look like a panel that's going to play but street rules, com eon. Fox News, "Ingraham: Democrats racing to the left," 28 June 2018 In another, Terry and Andy travel back in time to different eons. Clarissa Sebag-montefiore, New York Times, "Andy Griffiths, the Down-Under Kids’ Author Known for His Butt Jokes, Now Builds and Builds on His Hit ‘Treehouse’ Series," 9 Mar. 2018 Nori’s crispiness comes from the seaweed’s eons of coping with the punishing realities of coastal living. Ali Bouzari, SFChronicle.com, "Housemade: The magic of Liholiho Yacht Club," 22 June 2018 An eon or two ago, Eastman Kodak was a bleeding-edge technology company. Kevin Roose, New York Times, "Kodak’s Dubious Cryptocurrency Gamble," 30 Jan. 2018 With each brushstroke, grain by grain, they are transported back through the eons, as a distant lizard roars. Mark Washburn, charlotteobserver, "The Dinosaur King in the Queen City? Charlotte kids might not believe the size of this experience | Charlotte Observer," 25 May 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.

See More

First Known Use of eon

circa 1642, in the meaning defined at sense 1

History and Etymology for eon

Latin, from Greek aiōn — more at aye entry 3

Keep scrolling for more

Learn More about eon

Dictionary Entries near eon






eo nomine


Statistics for eon

Last Updated

3 Sep 2018

Look-up Popularity

Time Traveler for eon

The first known use of eon was circa 1642

See more words from the same year

Keep scrolling for more

More Definitions for eon


Kids Definition of eon

variant of

Keep scrolling for more

Comments on eon

What made you want to look up eon? Please tell us where you read or heard it (including the quote, if possible).


to reject or criticize sharply

Get Word of the Day daily email!

Test Your Vocabulary

Words from Greek and Roman Mythology Quiz

  • the-triumph-of-venus-by-alessandro-magnasco
  • Boreal comes from the name of the ancient Greek god of which wind?
Spell It

Can you spell these 10 commonly misspelled words?


Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!