simple vs simpleness

simple and simpleness both are nouns.

Word	Noun	Adjective	Verb	Adverb
simple	Yes	Yes	No	No
simpleness	Yes	No	No	No

simple (noun)	simpleness (noun)
a person lacking intelligence or common sense	the quality of being simple or uncompounded
any herbaceous plant having medicinal properties	lack of ornamentation
	freedom from difficulty or hardship or effort
	a lack of penetration or subtlety

simple (adjective)	simpleness (adjective)
(botany) of leaf shapes; of leaves having no divisions or subdivisions
having few parts; not complex or complicated or involved
easy and not involved or complicated
exhibiting childlike simplicity and credulity
unornamented
lacking mental capacity and subtlety
apart from anything else; without additions or modifications