poor vs deficient

poor is a noun but deficient is not a noun.

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

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

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