noun a genus of bivalve shells; the hammer shell.
2. malleus ·noun one of the hard lateral pieces of the mastax of rotifera. ·see mastax.
3. malleus ·noun 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.