ETYM Gael. clann offspring, descendants; akin to Irish clann, cland, offspring, tribe, family; perh. from Latin plania scion, slip, cutting. Related to Plant.
1. A tribe or collection of families, united under a chieftain, regarded as having the same common ancestor, and bearing the same surname.
2. A clique; a sect, society, or body of persons; esp., a body of persons united by some common interest or pursuit; -- sometimes used contemptuously.
Social grouping based on kinship. Some traditional societies are organized by clans, which are either matrilineal or patrilineal, and whose members must marry into another clan in order to avoid in-breeding.
Familiar examples are the Highland clans of Scotland. Theoretically each clan is descended from a single ancestor from whom the name is derived—for example, clan MacGregor (“son of Gregor”).