Source : Webster's Revised Unabridged Dictionary (1913)

Hammer \Ham"mer\, n. [OE. hamer, AS. hamer, hamor; akin to D.
   hamer, G. & Dan. hammer, Sw. hammare, Icel. hamarr, hammer,
   crag, and perh. to Gr. ? anvil, Skr. a?man stone.]
   1. An instrument for driving nails, beating metals, and the
      like, consisting of a head, usually of steel or iron,
      fixed crosswise to a handle.

            With busy hammers closing rivets up.  --Shak.

   2. Something which in firm or action resembles the common
      hammer; as:
      (a) That part of a clock which strikes upon the bell to
          indicate the hour.
      (b) The padded mallet of a piano, which strikes the wires,
          to produce the tones.
      (c) (Anat.) The malleus. See under {Ear}. (Gun.) That part
          of a gunlock which strikes the percussion cap, or
          firing pin; the cock; formerly, however, a piece of
          steel covering the pan of a flintlock musket and
          struck by the flint of the cock to ignite the priming.
      (e) Also, a person of thing that smites or shatters; as,
          St. Augustine was the hammer of heresies.

                He met the stern legionaries [of Rome] who had
                been the ``massive iron hammers'' of the whole
                earth.                            --J. H.
                                                  Newman.

   {Atmospheric hammer}, a dead-stroke hammer in which the
      spring is formed by confined air.

   {Drop hammer}, {Face hammer}, etc. See under {Drop}, {Face},
      etc.

   {Hammer fish}. See {Hammerhead}.

   {Hammer hardening}, the process of hardening metal by
      hammering it when cold.

   {Hammer shell} (Zo["o]l.), any species of {Malleus}, a genus
      of marine bivalve shells, allied to the pearl oysters,
      having the wings narrow and elongated, so as to give them
      a hammer-shaped outline; -- called also {hammer oyster}.
      

   {To bring to the hammer}, to put up at auction.