Source : Webster's Revised Unabridged Dictionary (1913)

Emissary \Em"is*sa*ry\, n.; pl. {Emissaries}. [L. emissarius,
   fr. emittere, emissum, to send out: cf. F. ['e]missaire. See
   {Emit}.]
   An agent employed to advance, in a covert manner, the
   interests of his employers; one sent out by any power that is
   at war with another, to create dissatisfaction among the
   people of the latter.

         Buzzing emissaries fill the ears Of listening crowds
         with jealousies and fears.               --Dryden.

   Syn: {Emissary}, {Spy}.

   Usage: A spy is one who enters an enemy's camp or territories
          to learn the condition of the enemy; an emissary may
          be a secret agent appointed not only to detect the
          schemes of an opposing party, but to influence their
          councils. A spy must be concealed, or he suffers
          death; an emissary may in some cases be known as the
          agent of an adversary without incurring similar
          hazard.

Emissary \Em"is*sa*ry\, a.
   1. Exploring; spying. --B. Jonson.

   2. (Anat.) Applied to the veins which pass out of the cranium
      through apertures in its walls.

Source : WordNet®

emissary
     n : someone sent on a mission to represent the interests of
         someone else [syn: {envoy}]