Word Origin & History
brother
O.E. broþor, from P.Gmc. *brothar, from PIE base *bhrater (cf. Gk. phratér, L. frater, O.Ir. brathir, Skt. bhrátár-, O.Pers. brata, Goth. bróþar, O.Prus. brati, O.C.S. bratru "brother"). As a familiar term of address from one man to another, it is attested from 1912 in U.S. slang; the specific use among blacks is recorded from 1973. Alternate pl. brethren was predominant c.1200-1600s, but survived only in religious usage. Colloquial shortening bro is attested from 1666. Brotherhood is M.E. broiþerhede (c.1300). In Arabic, Urdu, Swahili, etc., brother-in-law, when addressed to a male who is not a brother-in-law, is an extreme insult, with implications of "I slept with your sister."