a roman officer who controlled or superintended a particular command, charge, department, etc.; as, the prefect of the aqueducts; the prefect of a camp, of a fleet, of the city guard, of provisions; the pretorian prefect, who was commander of the troops guarding the emperor's person.-a superintendent of a department who has control of its police establishment, together with extensive powers of municipal regulation.-in the greek and roman catholic churches, a title of certain dignitaries below the rank of bishop.