Turnkey
The Cyclopedic Law Dictionary · Walter A. Shumaker and George Foster Longsdorf; ed. James C. Cahill · 1922
The Cyclopedic Law Dictionary
A person under the superintendence of a jailer, whose employment is to open and fasten the prison doors, and to prevent the prisoners from escaping. It is his duty to use due diligence; and he may be punished for neglect