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

From the Asian elephant to the gharial, there’s a staggering array of native wildlife that’s been calling India home for eons, with no shortage of iconic mammals, birds and reptiles to be found during a visit. —Jared Ranahan, Forbes.com, 3 Apr. 2025

His size, skill set, versatility, vision and feel for the game form the most complete package the sport has seen in eons. —Jon Wilner, Mercury News, 31 Mar. 2025

Though the global changes of the Cryogenic happened eons ago, Kirkland sees parallels with the wide-scale climate changes of today. —Ars Technica, 28 Feb. 2025

Most fundamentally, quantum computing promises to provide answers to problems previously thought unsolvable—puzzles that would take eons for the world’s best classical computers to crack. —Charina Chou, Foreign Affairs, 7 Jan. 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