Source : Webster's Revised Unabridged Dictionary (1913)

Agitator \Ag"i*ta`tor\, n. [L.]
   1. One who agitates; one who stirs up or excites others; as,
      political reformers and agitators.

   2. (Eng. Hist.) One of a body of men appointed by the army,
      in Cromwell's time, to look after their interests; --
      called also {adjutators}. --Clarendon.

   3. An implement for shaking or mixing.

Source : WordNet®

agitator
     n : one who agitates; a political troublemaker [syn: {fomenter}]