deficiency vs deficient

deficiency is a noun but deficient is not a noun.

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

deficiency (noun)	deficient (noun)
lack of an adequate quantity or number
the state of needing something that is absent or unavailable

deficiency (adjective)	deficient (adjective)
	of a quantity not able to fulfill a need or requirement
	inadequate in amount or degree
	falling short of some prescribed norm