aeon aeons in AM, use eon An aeon is an extremely long period of time. Aeons ago, there were deserts where there is now fertile land. = age. eon an extremely long period of time. or eon In Gnosticism or Manichaeism, one of the orders of spirits, or spheres of being, emanating from the godhead. The first aeon emanated directly from unmanifested divinity and was charged with divine force. Aeons increased in number and decreased in divine energy with increased remoteness from the divinity. At sufficient remoteness, error became possible and was the source of the material universe. Aeons may be viewed positively, as embodiments of the divine, or negatively, as media through which the soul must pass to reach its divine origin. Archean Eon Archeozoic Eon Archaean Eon Phanerozoic Eon Proterozoic Eon