united vs joint

united is not a noun while joint is a noun.

Word	Noun	Adjective	Verb	Adverb
united	No	Yes	No	No
joint	Yes	Yes	Yes	No

united (noun)	joint (noun)
	marijuana leaves rolled into a cigarette for smoking
	junction by which parts or objects are joined together
	a disreputable place of entertainment
	(anatomy) the point of connection between two bones or elements of a skeleton (especially if it allows motion)
	a piece of meat roasted or for roasting and of a size for slicing into more than one portion
	the shape or manner in which things come together and a connection is made

united (adjective)	joint (adjective)
characterized by unity; being or joined into a single entity	united or combined
of or relating to two people who are married to each other	involving both houses of a legislature
involving the joint activity of two or more	affecting or involving two or more