undecomposable vs simple

undecomposable is not a noun while simple is a noun.

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

undecomposable (noun)	simple (noun)
	a person lacking intelligence or common sense
	any herbaceous plant having medicinal properties

undecomposable (adjective)	simple (adjective)
representing the furthest possible extent of analysis or division into parts	(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