eon

noun

ˈē-ən  ˈē-ˌän 

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

For eons, gay men (and their enablers) have been passing down misinformation about something that is admittedly precarious, yet more simple than it's made out to be. —Fran Tirado, Them, 20 Dec. 2024

The selection makes sense in that the Bears have a large alumni base in Southern California and did not play a regular season game at USC or UCLA for the first time in eons. —Jon Wilner, The Mercury News, 8 Dec. 2024

The conditions inside it are similar to those that were common throughout the universe 5 billion years ago, eons closer to when star formation was at its peak. —Ross Andersen, The Atlantic, 5 Nov. 2024

If scientists can do that, however, next-generation geothermal power could supply clean energy for eons. —Brent Crane, The New Yorker, 2 Mar. 2025

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

Rhymes for eon

• adlerian
• caesarian
• cyclopean
• empyrean
• euclidean
• european
• grammarian
• hercynian
• huronian
• jacobean
• kampuchean
• maccabean

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