The Collaborative International Dictionary of English v.0.48:

Conservator \Con"ser*va`tor\ (?; 277), n. [L.: cf. F.
   conservateur.]
   1. One who preserves from injury or violation; a protector; a
      preserver.
      [1913 Webster]

            The great Creator and Conservator of the world.
                                                  --Derham.
      [1913 Webster]

   2. (Law)
      (a) An officer who has charge of preserving the public
          peace, as a justice or sheriff.
      (b) One who has an official charge of preserving the
          rights and privileges of a city, corporation,
          community, or estate.
          [1913 Webster]

                The lords of the secret council were likewise
                made conservators of the peace of the two
                kingdoms.                         --Clarendon.
          [1913 Webster]

                The conservator of the estate of an idiot.
                                                  --Bouvier.
          [1913 Webster]

   Conservators of the River Thames, a board of commissioners
      instituted by Parliament to have the conservancy of the
      Thames.
      [1913 Webster]