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

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

This modest study of unlikely community found at the end of the world — or damn near close enough — gains a more mythic sweep as the island is faced with a perilous storm, expected to bring destructive flooding on a scale not seen in eons, and this ragtag crew must weather it together. —Guy Lodge, Variety, 20 Feb. 2025

Scientists say the rings offer a unique opportunity to dissect the complex interplay of stellar outflow over eons. —Sharmila Kuthunur, Space.com, 15 Apr. 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