difficult vs difficultness

difficult is not a noun while difficultness is a noun.

Word	Noun	Adjective	Verb	Adverb
difficult	No	Yes	No	No
difficultness	Yes	No	No	No

difficult (noun)	difficultness (noun)
	the quality of being almost beyond one's ability to deal with and requiring a great effort to achieve a positive result

difficult (adjective)	difficultness (adjective)
not easy; requiring great physical or mental effort to accomplish or comprehend or endure
hard to control