upright vs unbowed

upright is a noun but unbowed is not a noun.

Word	Noun	Adjective	Verb	Adverb
upright	Yes	Yes	No	No
unbowed	No	Yes	No	No

upright (noun)	unbowed (noun)
a piano with a vertical sounding board
a vertical structural member as a post or stake

upright (adjective)	unbowed (adjective)
upright in position or posture	erect in posture
of moral excellence	not forced to bow down to a conqueror
in a vertical position; not sloping