ill vs laid up

ill is a noun but laid up is not a noun.

Word	Noun	Adjective	Verb	Adverb
ill	Yes	Yes	No	Yes
laid up	No	Yes	No	No

ill (noun)	laid up (noun)
an often persistent bodily disorder or disease; a cause for complaining

ill (adjective)	laid up (adjective)
affected by an impairment of normal physical or mental function	ill and usually confined
distressing
resulting in suffering or adversity
indicating hostility or enmity
presaging ill fortune

ill (adverb)	laid up (adverb)
(`ill' is often used as a combining form) in a poor or improper or unsatisfactory manner; not well
with difficulty or inconvenience; scarcely or hardly
unfavorably or with disapproval