The Collaborative International Dictionary of English v.0.48:

Mallet \Mal"let\, n. [F. maillet, dim. of mail. See Mall a
   beetle.]
   A small maul with a short handle, -- used esp. for driving a
   tool, as a chisel or the like; also, a light beetle with a
   long handle, -- used in playing croquet.
   [1913 Webster]

WordNet (r) 3.0 (2006):

mallet
    n 1: a sports implement with a long handle and a head like a
         hammer; used in sports (polo or croquet) to hit a ball
    2: a light drumstick with a rounded head that is used to strike
       such percussion instruments as chimes, kettledrums, marimbas,
       glockenspiels, etc. [syn: mallet, hammer]
    3: a tool resembling a hammer but with a large head (usually
       wooden); used to drive wedges or ram down paving stones or
       for crushing or beating or flattening or smoothing [syn:
       mallet, beetle]