best vs unsurpassable

best is a noun but unsurpassable is not a noun.

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

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

best (adjective)	unsurpassable (adjective)
(superlative of `good') having the most positive qualities	not to be exceeded
(comparative and superlative of `well') wiser or more advantageous and hence advisable

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

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