tribe 
(trīb)
(trīb)n.
1. 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.
2. A political, ethnic, or ancestral division of ancient states and cultures, especially:
a. Any of the three divisions of the ancient Romans, namely, the Latin, Sabine, and Etruscan.
b. Any of the 12 divisions of ancient Israel.
c. A phyle of ancient Greece.
3. A group of people sharing an occupation, interest, or habit: a tribe of graduate students.
4. Informal A large family.
5. Biology A taxonomic category ranking below a family or subfamily and above a genus and usually containing several genera.
[Middle English, from Old French tribu, from Latin tribus, division of the Roman people, perhaps of Etruscan origin or possibly from tri-, three; see trei- in the Appendix of Indo-European roots.]