harsh vs harshness

harsh is not a noun while harshness is a noun.

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

harsh (noun)	harshness (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

harsh (adjective)	harshness (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