sustain vs prop

sustain is not a noun while prop is a noun.

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

As verbs, prop is a hyponym of sustain; that is, prop is a word with a more specific, narrower meaning than sustain:

Other hyponyms of sustain include scaffold, block, carry, chock, buoy, buoy up, pole, bracket, underpin, prop up, shore, shore up, truss, brace.

sustain (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

sustain (verb)	prop (verb)
undergo (as of injuries and illnesses)	support by placing against something solid or rigid
establish or strengthen as with new evidence or facts
admit as valid
supply with necessities and support
provide with nourishment
be the physical support of; carry the weight of
lengthen or extend in duration or space