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

Blasting from the central galaxy — home to a black hole more than 400 million times our sun — is a powerful jet that could provide fresh clues about how galaxies and their black holes evolve in tandem over eons. —Sharmila Kuthunur, Space.com, 14 Jan. 2025

Yet the event’s infamous impactor was nothing compared with the asteroid that struck Earth 3.26 billion years ago, amid what scientists call the Archean eon of our planet’s 4.5-billion-year history. —Douglas Fox, Scientific American, 21 Oct. 2024

For eons, these creatures have thrived across the azure waters of the Maldives—and in the modern era, the Manta Retreat provides the perfect opportunity to marvel at these splendid fish in the flesh. —Jared Ranahan, Forbes, 24 Jan. 2025

The main ingredient in Immy, this beneficial bacteria is derived from soil and has helped humans for eons by reducing chronic inflammation. —Emily Orofino, Vogue, 24 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