extensive vs extensiveness

extensive is not a noun while extensiveness is a noun.

Word	Noun	Adjective	Verb	Adverb
extensive	No	Yes	No	No
extensiveness	Yes	No	No	No

extensive (noun)	extensiveness (noun)
	large or extensive in breadth or importance or comprehensiveness

extensive (adjective)	extensiveness (adjective)
of agriculture; increasing productivity by using large areas with minimal outlay and labor
broad in scope or content
large in spatial extent or range or scope or quantity