Tribe
Etymology

The modern English word tribe stems from Middle English tribu, which ultimately derives from Latin tribus. According to the Oxford English Dictionary, it remains unclear if this form is the result of a borrowing from a Romance language source (such as Old French tribu) or if the form is a result of borrowing directly from Latin (the Middle English plural tribuz 1250 may be a direct representation of Latin plural tribūs). Modern English tribe may also be a result of a common pattern wherein English borrows nouns directly from Latin and drops suffixes, including -us. Latin tribus is generally held by linguists to be a compound formed from two elements: tri- 'three' and bhu, bu, fu, a verbal root meaning 'to be'.

Latin tribus is held to derive from the Proto-Indo-European compound * tri-dʰh₁u/o- ('rendered in three, tripartite division'; compare with Umbrian trifu 'trinity, district', Sanskrit trídha 'threefold').
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