simple vs obtuse

simple is a noun but obtuse is not a noun.

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

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

simple (adjective)	obtuse (adjective)
(botany) of leaf shapes; of leaves having no divisions or subdivisions	of an angle; between 90 and 180 degrees
having few parts; not complex or complicated or involved	(of a leaf shape) rounded at the apex
easy and not involved or complicated	slow to learn or understand; lacking intellectual acuity
exhibiting childlike simplicity and credulity	lacking in insight or discernment
unornamented
lacking mental capacity and subtlety
apart from anything else; without additions or modifications