steepness vs steep

steepness and steep both are nouns.

Word	Noun	Adjective	Verb	Adverb
steepness	Yes	No	No	No
steep	Yes	Yes	Yes	No

steepness (noun)	steep (noun)
the property possessed by a slope that is very steep	a steep place (as on a hill)

steepness (adjective)	steep (adjective)
	having a sharp inclination
	of a slope; set at a high angle
	greatly exceeding bounds of reason or moderation

steepness (verb)	steep (verb)
	let sit in a liquid to extract a flavor or to cleanse
	devote (oneself) fully to