Source : Webster's Revised Unabridged Dictionary (1913)

Collusion \Col*lu"sion\, n. [L. collusio: cf. F. collusion. See
   {Collude}.]
   1. A secret agreement and cooperation for a fraudulent or
      deceitful purpose; a playing into each other's hands;
      deceit; fraud; cunning.

            The foxe, maister of collusion.       --Spenser.

            That they [miracles] be done publicly, in the face
            of the world, that there may be no room to suspect
            artifice and collusion.               --Atterbury.

            By the ignorance of the merchants or dishonesty of
            the weavers, or the collusion of both, the ware was
            bad and the price excessive.          --Swift.

   2. (Law) An agreement between two or more persons to defraud
      a person of his rights, by the forms of law, or to obtain
      an object forbidden by law. --Bouvier. Abbott.

   Syn: {Collusion}, {Connivance}.

   Usage: A person who is guilty of connivance intentionally
          overlooks, and thus sanctions what he was bound to
          prevent. A person who is guilty of collusion unites
          with others (playing into their hands) for fraudulent
          purposes.

Source : WordNet®

collusion
     n 1: secret agreement
     2: agreement on a secret plot [syn: {connivance}]