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

Synonyms of eon

• forever
• months
• long
• age

Examples of eon in a Sentence

Recent Examples on the Web

The best buddy cop movie in eons has arrived in the form of Zootopia 2. —Pamela McClintock, HollywoodReporter, 27 Nov. 2025

At least some evidence suggests that NGC 2775 developed its odd shape after merging with other galaxies eons ago. —Andrew Paul, Popular Science, 26 Nov. 2025

People have been settling in Taos for centuries, eons, inspired to create a life there, in some cases with their own ideas about protecting, enhancing, and animating the landscape. —Michael Paterniti, Travel + Leisure, 14 Nov. 2025

With the midterm election still nearly a year off — and the 2028 presidential contest eons away — many of those angry or despondent over the benighted state of our union desperately wanted to do something to push back. —Mark Z. Barabak, Mercury News, 8 Nov. 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