or ae·on

[ ee-uhn, ee-on ]
See synonyms for eon on Thesaurus.com
  1. an indefinitely long period of time; age.

  2. the largest division of geologic time, comprising two or more eras.

  1. Astronomy. one billion years.

Origin of eon

see origin at aeon

Words Nearby eon

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use eon in a sentence

  • Bush ran his last competitive race in 1998, an eon ago in political terms.

  • Each change was supposed to denote the birth of some angel or celestial being known as an eon.

  • Action with a purpose is deliberate; it involves a consciously foreseen end and a mental weighing of considerations pro and eon.

  • He descended to the edge of the clearing and picked his way through the debris of some eon-old geologic catastrophe.

    First on the Moon | Jeff Sutton
  • After what seemed an eon it struck the edge of the subway kiosk, bounced like a rag doll and sprawled across the pavement.

    The End of Time | Wallace West
  • After what seemed an eon of waiting, he ventured another look ahead.

    The Valley of the Giants | Peter B. Kyne

British Dictionary definitions for eon


/ (ˈiːən, ˈiːɒn) /

  1. the usual US spelling of aeon

  2. geology the longest division of geological time, comprising two or more eras

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for eon


[ ēŏn′ ]

  1. The longest division of geologic time, containing two or more eras.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.