untarnished vs stainless

untarnished is not a noun while stainless is a noun.

Word	Noun	Adjective	Verb	Adverb
untarnished	No	Yes	No	No
stainless	Yes	Yes	No	No

As adjectives, untarnished and stainless are synonyms defined as:

Other synonyms of untarnished include unstained, unsullied, untainted.

untarnished (noun)	stainless (noun)
	steel containing chromium that makes it resistant to corrosion

untarnished (adjective)	stainless (adjective)
(of reputation) free from blemishes	(of reputation) free from blemishes