cousin vs relative

cousin and relative both are nouns.

Word	Noun	Adjective	Verb	Adverb
cousin	Yes	No	No	No
relative	Yes	Yes	No	No

As nouns, relative is a hypernym of cousin; that is, relative is a word with a broader meaning than cousin:

Other hypernyms of cousin include relation.

cousin (noun)	relative (noun)
the child of your aunt or uncle	an animal or plant that bears a relationship to another (as related by common descent or by membership in the same genus)
	a person related by blood or marriage

cousin (adjective)	relative (adjective)
	estimated by comparison; not absolute or complete
	properly related in size or degree or other measurable characteristics; usually followed by `to'