Definition of aeon in English:

Share this entry


Pronunciation: /ˈiːən/
(US or technical also eon)


1 (often aeons) An indefinite and very long period of time: he reached the crag aeons before I arrived
More example sentences
  • It is ages and aeons since I have been to the Hills.
  • I'll spend aeons staring at bottles of expensive shampoo humming ‘Maybe this time’.
  • Just after that, she started going out with a mutual friend of ours, who I'd dated aeons ago and was still friendly with.
1.1 Astronomy & Geology A unit of time equal to a thousand million years.
Example sentences
  • Because they have succumbed to erosion and weathering, perhaps for aeons, these craters are notoriously difficult to spot.
  • It's a rock place, a world of eons and eras and millions of years conflated to timelessness.
  • Over the eons the lunar spin rate has been damped by Earth's gravity, because the Moon's mass distribution is not uniform.
1.2 Geology A major division of geological time, subdivided into eras: the Precambrian aeon
More example sentences
  • The record has been much deformed, reconstituted, and obliterated during the subsequent Proterozoic and Phanerozoic eons.
  • The rocks dated back into the Archean eon, before 2.5 billion years ago.
  • These creatures were direct descendants of the great dinosaurs of the long past Mesozoic Aeon.
2 Philosophy (In Neoplatonism, Platonism, and Gnosticism) a power existing from eternity; an emanation or phase of the supreme deity.
Example sentences
  • He goes on to note that all aeons emanate from it.
  • This aeon is the image of the eternal age of the next life.
  • Whether that master be regarded as a sage or as a Gnostic aeon, the orthodox view of him would be seriously challenged.


Mid 17th century: via ecclesiastical Latin from Greek aiōn 'age'.

  • This entered English via ecclesiastical Latin from Greek aiōn ‘age’ and is usually used in the plural in phrases such as aeons ago.

Share this entry

What do you find interesting about this word or phrase?

Comments that don't adhere to our Community Guidelines may be moderated or removed.