inept vs ineptness

inept is not a noun while ineptness is a noun.

Word	Noun	Adjective	Verb	Adverb
inept	No	Yes	No	No
ineptness	Yes	No	No	No

inept (noun)	ineptness (noun)
	the quality of having the wrong properties for a specific purpose
	unskillfulness resulting from a lack of training

inept (adjective)	ineptness (adjective)
generally incompetent and ineffectual
not elegant or graceful in expression
revealing lack of perceptiveness or judgment or finesse