Encyclopædia Britannica, Ninth Edition/Æon
For works with similar titles, see Aeon.
Æon (αἰών), a space of time, was often used in Greek to denote indefinite or infinite duration; and hence, by metonymy, for a being that exists for ever. In the latter sense it was chiefly used by the Gnostic sects to denote those eternal beings or manifestations which emanated from the one incomprehensible and ineffable God. See Gnosticism.