unsuitableness vs ineptness

unsuitableness and ineptness both are nouns.

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

As nouns, unsuitableness and ineptness are synonyms defined as:

unsuitableness and ineptness: the quality of having the wrong properties for a specific purpose

Other synonyms of unsuitableness include unsuitability.

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