aeon

from The Century Dictionary.

• noun etc. See eon, eonian, etc.

from the GNU version of the Collaborative International Dictionary of English.

• noun A period of immeasurable duration. See eon.
• noun (Gnosticism) a divine power or nature emanating from the Supreme Being and playing various roles in the operation of the universe.
• noun the longest division of geological time; two or more eras.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Australia, New Zealand, UK Alternative spelling of eon.
• noun Gnosticism A spirit being emanating from the Godhead.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the longest division of geological time
• noun an immeasurably long period of time
• noun (Gnosticism) a divine power or nature emanating from the Supreme Being and playing various roles in the operation of the universe