The Collaborative International Dictionary of English v.0.48:

Binocle \Bin"o*cle\, n. [F. binocle; L. bini two at a time +
   oculus eye.] (Opt.)
   A dioptric telescope, fitted with two tubes joining, so as to
   enable a person to view an object with both eyes at once; a
   double-barreled field glass or an opera glass.
   [1913 Webster]