"wall enclosing an outer court," c.1300, baylle, variant of bail, from O.Fr. bail "stake, pallisade, brace," of unknown origin, perhaps ultimately connected to L. bacula "sticks," on notion of "stakes, palisade fence." Old Bailey, seat of Central Criminal Court in London, was so called because it stood
within the ancient bailey of the city wall. The surname Bailey usually is from O.Fr. bailli, a later form of 'baillif (q.v.).