n. One who is appointed to superintend or preside over something; the chief or head of certain bodies.n. The keeper of a prison; a chief jailer.n. Formerly, one holding a position in the English schools of fence higher than that of scholar and lower than that of master.n. A temporary prison in which the military police confine prisoners until they are disposed of.n. In the navy, an officer who is charged with the safe-keeping of a prisoner, pending his trial by a court martial, and who is responsible for his production before the court whenever his presence is required.