unbowed vs upright

unbowed is not a noun while upright is a noun.

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

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

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