The Collaborative International Dictionary of English v.0.48:

Throwing stick \Throw"ing stick`\ (Anthropol.)
   An instrument used by various savage races for throwing a
   spear; -- called also throw stick and spear thrower. One
   end of the stick receives the butt of the spear, as upon a
   hook or thong, and the other end is grasped with the hand,
   which also holds the spear, toward the middle, above it with
   the finger and thumb, the effect being to bring the place of
   support nearer the center of the spear, and practically
   lengthen the arm in the act of throwing. In Mexico, one such
   device is called the atlatl.
   [Webster 1913 Suppl. +PJC]
   [1913 Webster]

WordNet (r) 3.0 (2006):

throw stick
    n 1: a curved piece of wood; when properly thrown will return to
         thrower [syn: boomerang, throwing stick, throw stick]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "throw stick":
   Irish confetti, arbalest, ballista, bola, bolt, boomerang,
   brickbat, catapult, countermissile, missile, projectile, rock,
   rocket, sling, slingshot, stone, throwing-stick, torpedo,
   trebuchet, waddy, wommera