orthostatic vs upright

orthostatic is not a noun while upright is a noun.

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

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

orthostatic (adjective)	upright (adjective)
pertaining to an upright standing posture	upright in position or posture
	of moral excellence
	in a vertical position; not sloping