Source : Webster's Revised Unabridged Dictionary (1913)

Quaker \Quak"er\, n.
   1. One who quakes.

   2. One of a religious sect founded by George {Fox}, of
      Leicestershire, England, about 1650, -- the members of
      which call themselves Friends. They were called Quakers,
      originally, in derision. See {Friend}, n., 4.

            Fox's teaching was primarily a preaching of
            repentance . . . The trembling among the listening
            crowd caused or confirmed the name of Quakers given
            to the body; men and women sometimes fell down and
            lay struggling as if for life.        --Encyc. Brit.

   3. (Zo["o]l.)
      (a) The nankeen bird.
      (b) The sooty albatross.
      (c) Any grasshopper or locust of the genus ({Edipoda}; --
          so called from the quaking noise made during flight.

   {Quaker buttons}. (Bot.) See {Nux vomica}.

   {Quaker gun}, a dummy cannon made of wood or other material;
      -- so called because the sect of Friends, or Quakers, hold
      to the doctrine, of nonresistance.

   {Quaker ladies} (Bot.), a low American biennial plant
      ({Houstonia c[ae]rulea}), with pretty four-lobed corollas
      which are pale blue with a yellowish center; -- also
      called {bluets}, and {little innocents}.

Source : WordNet®

Quaker gun
     n : a dummy gun or piece of artillery made usually of wood