eonian vs eon

eonian is not a noun while eon is a noun.

Word	Noun	Adjective	Verb	Adverb
eonian	No	Yes	No	No
eon	Yes	No	No	No

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

eonian (adjective)	eon (adjective)
of or relating to a geological eon (longer than an era)
continuing forever or indefinitely