Source : Webster's Revised Unabridged Dictionary (1913)

Binnacle \Bin"na*cle\, n. [For bittacle, corrupted (perh. by
   influence of bin) fr. Pg. bitacola binnacle, fr. L.
   habitaculum dwelling place, fr. habitare to dwell. See
   {Habit}, and cf. {Bittacle}.] (Naut.)
   A case or box placed near the helmsman, containing the
   compass of a ship, and a light to show it at night. --Totten.

Source : WordNet®

binnacle
     n : a nonmagnetic housing for a ship's compass (usually in front
         of the helm)