Source : Webster's Revised Unabridged Dictionary (1913)

Malleus \Mal"le*us\, n.; pl. {Mallei}. [L., hammer. See {Mall} a
   beetle.]
   1. (Anat.) The outermost of the three small auditory bones,
      ossicles; the hammer. It is attached to the tympanic
      membrane by a long process, the handle or manubrium. See
      Illust. of {Far}.

   2. (Zo["o]l.) One of the hard lateral pieces of the mastax of
      Rotifera. See {Mastax}.

   3. (Zo["o]l.) A genus of bivalve shells; the hammer shell.

Source : WordNet®

malleus
     n : the ossicle attached to the eardrum [syn: {hammer}]
     [also: {mallei} (pl)]