Source : Webster's Revised Unabridged Dictionary (1913)

Stirrer \Stir"rer\, n.
   One who, or that which, stirs something; also, one who moves
   about, especially after sleep; as, an early stirrer. --Shak.

   {Stirrer up}, an instigator or inciter. --Atterbury.

Source : WordNet®

stirrer
     n 1: a person who spreads frightening rumors and stirs up trouble
          [syn: {scaremonger}]
     2: an implement used for stirring