The Collaborative International Dictionary of English v.0.48:

Turnkey \Turn"key`\ (t[^u]rn"k[=e]`), n.; pl. Turnkeys
   (t[^u]r"k[=e]z`).
   1. A person who has charge of the keys of a prison, for
      opening and fastening the doors; a warder.
      [1913 Webster]

   2. (Dentistry) An instrument with a hinged claw, -- used for
      extracting teeth with a twist.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

turnkey \turn"key`\ (t[^u]rn"k[=e]`), a.
   Of or pertaining to a building, complex device, system, or
   industrial installation which is sold by a contractor only
   after it is ready for immediate occupation or use; fully
   functional and ready for use; -- used of complex systems of a
   type which often require preparation or installation by the
   user before being capable of functioning as intended; as, a
   turnkey ethylene production plant; a turnkey apartment
   building.
   [PJC]

WordNet (r) 3.0 (2006):

turnkey
    n 1: someone who guards prisoners [syn: prison guard,
         jailer, jailor, gaoler, screw, turnkey]