A unit of sociopolitical organization consisting of a number of families, clans, or other groups who share a common ancestry and culture and among whom leadership is typically neither formalized nor permanent. A political, ethnic, or ancestral division of ancient states and cultures, especially: Any of the three divisions of the ancient Romans, namely, the Latin, Sabine, and Etruscan. Any of the 12 divisions of ancient Israel. A phyle of ancient Greece. A group of people sharing an occupation, interest, or habit: a tribe of graduate students. Informal A large family. Biology A taxonomic category placed between a subfamily and a genus or between a suborder and a family and usually containing several genera.