simpleness vs simple

simpleness and simple both are nouns.

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

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

simpleness (adjective)	simple (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