deficient vs poor

deficient is not a noun while poor is a noun.

Word	Noun	Adjective	Verb	Adverb
deficient	No	Yes	No	No
poor	Yes	Yes	No	No

deficient (noun)	poor (noun)
	people without possessions or wealth (considered as a group)

deficient (adjective)	poor (adjective)
of a quantity not able to fulfill a need or requirement	having little money or few possessions
inadequate in amount or degree	lacking in quality or substances
falling short of some prescribed norm	characterized by or indicating poverty
	of insufficient quantity to meet a need
	deserving or inciting pity