linear vs simple

linear is not a noun while simple is a noun.

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

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

linear (adjective)	simple (adjective)
of or in or along or relating to a line; involving or having a single dimension	(botany) of leaf shapes; of leaves having no divisions or subdivisions
designating or involving an equation whose terms are of the first degree	having few parts; not complex or complicated or involved
of a circuit or device having an output that is proportional to the input	easy and not involved or complicated
measured lengthwise	exhibiting childlike simplicity and credulity
(of a leaf shape) long and narrow	unornamented
	lacking mental capacity and subtlety
	apart from anything else; without additions or modifications