sustain vs brace

sustain is not a noun while brace is a noun.

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

As verbs, brace is a hyponym of sustain; that is, brace 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, prop up, shore, shore up, truss.

sustain (noun)	brace (noun)
	a structural member used to stiffen a framework
	a carpenter's tool having a crank handle for turning and a socket to hold a bit for boring
	an appliance that corrects dental irregularities
	a support that steadies or strengthens something else
	elastic straps that hold trousers up
	a rope on a square-rigged ship that is used to swing a yard about and secure it
	either of two punctuation marks ({ or }) used to enclose textual material
	a set of two similar things considered as a unit
	two items of the same kind

sustain (verb)	brace (verb)
undergo (as of injuries and illnesses)	cause to be alert and energetic
establish or strengthen as with new evidence or facts	support by bracing
admit as valid	support or hold steady and make steadfast, with or as if with a brace
supply with necessities and support	prepare (oneself), often but not necessarily for something unpleasant or difficult
provide with nourishment
be the physical support of; carry the weight of
lengthen or extend in duration or space