rheumatoid vs arthritic

rheumatoid is not a noun while arthritic is a noun.

Word	Noun	Adjective	Verb	Adverb
rheumatoid	No	Yes	No	No
arthritic	Yes	Yes	No	No

As adjectives, rheumatoid and arthritic are synonyms defined as:

Other synonyms of rheumatoid include creaky, rheumatic, rheumy.

rheumatoid (noun)	arthritic (noun)
	a person afflicted with arthritis

rheumatoid (adjective)	arthritic (adjective)
of or pertaining to arthritis	of or pertaining to arthritis