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

Some magnetic properties of those particles might have been lost eons ago, but so much more could be gained in the future from what remains. Nature Communications, 2024. —Elizabeth Rayne, Ars Technica, 19 May 2024

There are still many questions about how our own solar system came to be and evolved over the eons into its current configuration. —Phil Plait, Scientific American, 15 Mar. 2024

In fact, snakes are just one of more than 30 groups of lizards that each evolved away their legs separately over the eons. —Joshua Rapp Learn, Discover Magazine, 4 June 2024

The story behind the park’s dramatic cliffs is all about the Ice Age melting, with floods that carved the stark scenery of eastern Washington eons ago. —Jd Shadel, Condé Nast Traveler, 14 Mar. 2023

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

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