sick vs sick-abed

sick is a noun but sick-abed is not a noun.

Word	Noun	Adjective	Verb	Adverb
sick	Yes	Yes	Yes	No
sick-abed	No	Yes	No	No

sick (noun)	sick-abed (noun)
people who are sick

sick (adjective)	sick-abed (adjective)
affected by an impairment of normal physical or mental function	confined to bed (by illness)
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)	sick-abed (verb)
eject the contents of the stomach through the mouth