PENITENTIARY, a prison or place of confinement for criminals, in which the prisoners are made to labour, and a system of discipline is employed for effecting their reformation. The building is so constructed that the overseer from a central station can observe the conduct of every individual. There is an establishment of this kind at Milbank, near London, but the building is not yet finished. It is intended for the reception of such criminals as have hitherto been transported to New South Wales, for a less period than during life.