Source : Webster's Revised Unabridged Dictionary (1913)

Beater \Beat"er\ (b[=e]t"[~e]r), n.
   1. One who, or that which, beats.

   2. A person who beats up game for the hunters. --Black.

Source : WordNet®

beater
     n 1: a worker who rouses wild game from under cover for a hunter
     2: an implement for beating