semi-upright vs upright

semi-upright is not a noun while upright is a noun.

Word	Noun	Adjective	Verb	Adverb
semi-upright	No	Yes	No	No
upright	Yes	Yes	No	No

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

semi-upright (adjective)	upright (adjective)
of animals that are partly erect	upright in position or posture
	of moral excellence
	in a vertical position; not sloping