second cousin vs relative

second cousin and relative both are nouns.

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

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

Other hypernyms of second cousin include relation.

second cousin (noun)	relative (noun)
a child of a first cousin of one's parent	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

second 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'