sick vs be sick

sick is a noun but be sick is not a noun.

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

As verbs, sick and be sick are synonyms defined as:

sick (noun)	be sick (noun)
people who are sick

sick (adjective)	be sick (adjective)
affected by an impairment of normal physical or mental function
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

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