sickly vs sick

sickly is not a noun while sick is a noun.

Word	Noun	Adjective	Verb	Adverb
sickly	No	Yes	No	No
sick	Yes	Yes	Yes	No

sickly (noun)	sick (noun)
	people who are sick

sickly (adjective)	sick (adjective)
somewhat ill or prone to illness	affected by an impairment of normal physical or mental function
unhealthy looking	shockingly repellent; inspiring horror
	having a strong distaste from surfeit
	affected with madness or insanity
	deeply affected by a strong feeling
	(of light) lacking in intensity or brightness; dim or feeble
	feeling nausea; feeling about to vomit

sickly (verb)	sick (verb)
	eject the contents of the stomach through the mouth