sustainment vs sustain

sustainment is a noun but sustain is not a noun.

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

sustainment (noun)	sustain (noun)
the act of sustaining life by food or providing a means of subsistence

sustainment (verb)	sustain (verb)
	undergo (as of injuries and illnesses)
	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