eonian vs everlasting

eonian is not a noun while everlasting is a noun.

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

As adjectives, eonian and everlasting are synonyms defined as:

Other synonyms of eonian include aeonian, ageless, eternal, perpetual, unceasing, unending.

eonian (noun)	everlasting (noun)
	any of various plants of various genera of the family Compositae having flowers that can be dried without loss of form or color

eonian (adjective)	everlasting (adjective)
of or relating to a geological eon (longer than an era)	continuing forever or indefinitely
continuing forever or indefinitely	without qualification; used informally as (often pejorative) intensifiers