parasite vs parasitical

parasite is a noun but parasitical is not a noun.

Word	Noun	Adjective	Verb	Adverb
parasite	Yes	No	No	No
parasitical	No	Yes	No	No

parasite (noun)	parasitical (noun)
an animal or plant that lives in or on a host (another animal or plant); it obtains nourishment from the host without benefiting or killing the host
a follower who hangs around a host (without benefit to the host) in hope of gain or advantage

parasite (adjective)	parasitical (adjective)
	relating to or caused by parasites
	of plants or persons; having the nature or habits of a parasite or leech; living off another