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 end goal is to not only recover nuclear fuel and isotopes, but to quickly reduce the US waste stockpile in decades rather than eons. — David Szondy august 22, New Atlas, 22 Aug. 2026

Throughout the five nights, the group performed 106 distinct songs with no repeats, many of which had not been aired in eons. — Jonathan Cohen, SPIN, 30 July 2026

There has been talk of getting the gang back together for a eons now, but nothing has come of it, unfortunately. — Paul Tassi, Forbes.com, 29 July 2026

Meta, Google, and Apple hadn’t put out an exciting new innovation in eons. — Annie Lowrey, The Atlantic, 29 June 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
• european
• grammarian
• hercynian
• huronian
• jacobean
• maccabean
• manichaean
• manichean
• mullerian

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