ix vs nine

ix is not a noun while nine is a noun.

Word	Noun	Adjective	Verb	Adverb
ix	No	Yes	No	No
nine	Yes	Yes	No	No

As adjectives, ix and nine are synonyms defined as:

ix and nine: denoting a quantity consisting of one more than eight and one less than ten

Other synonyms of ix include 9.

ix (noun)	nine (noun)
	one of four playing cards in a deck with nine pips on the face
	a team of professional baseball players who play and travel together
	the cardinal number that is the sum of eight and one

ix (adjective)	nine (adjective)
denoting a quantity consisting of one more than eight and one less than ten	denoting a quantity consisting of one more than eight and one less than ten