Meaning of 従姉 in Japanese

おまえの従姉だったよな。二年生、現生徒会役員。部活はバスケで、副キャプテンを務めてる。
It was your cousin. Second year, current member of student council, club activity is basketball, working as vice captain.

従姉妹にはね、もの凄いボインボインな子がいるんだよ？
Among my cousins, you know, there's a girl with the most enormous breasts.

ジャックはたしかメアリーのまたいとこだと思う。
Jack is Mary's second cousin, I believe.