unsuitability vs unsuitableness

unsuitability and unsuitableness both are nouns.

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

As nouns, unsuitability and unsuitableness are synonyms defined as:

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

Other synonyms of unsuitability include ineptness.

unsuitability (noun)	unsuitableness (noun)
the quality of having the wrong properties for a specific purpose	the quality of having the wrong properties for a specific purpose