prop up vs prop

prop up is not a noun while prop is a noun.

Word	Noun	Adjective	Verb	Adverb
prop up	No	No	Yes	No
prop	Yes	No	Yes	No

As verbs, prop up and prop are synonyms defined as:

Other synonyms of prop up include shore, shore up.

prop up (noun)	prop (noun)
	a support placed beneath or against something to keep it from shaking or falling
	a propeller that rotates to push against air
	any movable articles or objects used on the set of a play or movie

prop up (verb)	prop (verb)
support by placing against something solid or rigid	support by placing against something solid or rigid