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

These stellar exiles can travel across space for eons before ending up infiltrating unrelated nebulas like Sh2-46, according to the statement. —Sharmila Kuthunur, Space.com, 9 May 2025

Michelle was only two years older than me, but in preteen years, that is an eon. —Mara Wilson, Vulture, 18 Mar. 2025

Enter quantum computing and its mind-bending ability to harness strange quantum properties, such as tunneling and superposition, in order to solve certain complex problems in seconds rather than eons. —Bernard Marr, Forbes.com, 26 Mar. 2025

Despite the intervening eons, this pattern should still be etched across the cosmos in the spatial distributions of galaxies. —Meghan Bartels, Scientific American, 28 Feb. 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