unsurpassed vs best

unsurpassed is not a noun while best is a noun.

Word	Noun	Adjective	Verb	Adverb
unsurpassed	No	Yes	No	No
best	Yes	Yes	Yes	Yes

unsurpassed (noun)	best (noun)
	the supreme effort one can make
	the person who is most outstanding or excellent; someone who tops all others

unsurpassed (adjective)	best (adjective)
not capable of being improved on	(superlative of `good') having the most positive qualities
	(comparative and superlative of `well') wiser or more advantageous and hence advisable

unsurpassed (verb)	best (verb)
	get the better of

unsurpassed (adverb)	best (adverb)
	it would be sensible
	in a most excellent way or manner
	from a position of superiority or authority