harshness vs harsh

harshness is a noun but harsh is not a noun.

Word	Noun	Adjective	Verb	Adverb
harshness	Yes	No	No	No
harsh	No	Yes	No	No

harshness (noun)	harsh (noun)
the quality of being harsh or rough or grating to the senses
excessive sternness
the roughness of a substance that causes abrasions
the quality of being cruel and causing tension or annoyance

harshness (adjective)	harsh (adjective)
	of textures that are rough to the touch or substances consisting of relatively large particles
	sharply disagreeable; rigorous
	severe
	unkind or cruel or uncivil
	unpleasantly stern
	unpleasantly rough or jarring to the senses