itch vs itchy

itch is a noun but itchy is not a noun.

Word	Noun	Adjective	Verb	Adverb
itch	Yes	No	Yes	No
itchy	No	Yes	No	No

itch (noun)	itchy (noun)
an irritating cutaneous sensation that produces a desire to scratch
a strong restless desire
a contagious skin infection caused by the itch mite; characterized by persistent itching and skin irritation

itch (adjective)	itchy (adjective)
	causing an irritating cutaneous sensation; being affect with an itch
	nervous and unable to relax

itch (verb)	itchy (verb)
have a strong desire or urge to do something
have or perceive an itch
scrape or rub as if to relieve itching
cause to perceive an itch