表亲是指借着父母的兄弟姐妹而链接的血亲。父母的表亲对子女而言也是表亲，现代细分的时候称之为二代表亲，而父母的兄弟姊妹的直系后代则称之为一代表亲。以此类推，还有三代、四代等。如果一种表亲关系，并不是可用此种关系的亲属中，亲缘最近的（比如，“表兄弟”关系，最近的亲缘就是父母的兄弟姊妹的子女，属于一代表亲。而“表叔”关系最近的亲缘就是父母的一代表兄，属于本人的二代表亲），就会在前面加上远房二字加以区分，称为“远房表弟”,“远房表叔”等。同时，“远房表亲”也凡指一切非一代的表亲。

A cousin is a child of one's uncles and aunts.

Systems of "degrees" and "removals" are used in the English-speaking world to describe the exact relationship between two cousins (in the broad sense) and the ancestor they have in common. Various governmental entities have established systems for legal use that can more precisely specify kinships with common ancestors existing any number of generations in the past, though common usage often eliminates the degrees and removals and refers to people with common ancestry as simply "distant cousins" or "relatives".