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

But Villaraigosa left City Hall in 2013 — eons ago in the world of politics. —Los Angeles Times, 16 Mar. 2026

But that was more than five years ago — eons in American politics. —Frank Langfitt, NPR, 12 Mar. 2026

The best buddy cop movie in eons has arrived in the form of Zootopia 2. —Pamela McClintock, HollywoodReporter, 4 Mar. 2026

Fermentation is in it for the long game A process that’s no newbie, fermentation has been around for eons. —Scott Hocker, TheWeek, 20 Feb. 2026

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