Source : Webster's Revised Unabridged Dictionary (1913)

Weapon \Weap"on\ (?; 277), n. [OE. wepen, AS. w?pen; akin to OS.
   w?pan, OFries. w?pin, w?pen, D. wapen, G. waffe, OHG. waffan,
   w[=a]fan, Icel. v[=a]pn, Dan. vaaben, Sw. vapen, Goth. w?pna,
   pl.; of uncertain origin. Cf. {Wapentake}.]
   1. An instrument of offensive of defensive combat; something
      to fight with; anything used, or designed to be used, in
      destroying, defeating, or injuring an enemy, as a gun, a
      sword, etc.

            The weapons of our warfare are not carnal. --2 Cor.
                                                  x. 4.

            They, astonished, all resistance lost, All courage;
            down their idle weapons dropped.      --Milton.

   2. Fig.: The means or instrument with which one contends
      against another; as, argument was his only weapon.
      ``Woman's weapons, water drops.'' --Shak.

   3. (Bot.) A thorn, prickle, or sting with which many plants
      are furnished.

   {Concealed weapons}. See under {Concealed}.

   {Weapon salve}, a salve which was supposed to cure a wound by
      being applied to the weapon that made it. [Obs.] --Boyle.

Source : WordNet®

weapon
     n 1: any instrument or instrumentality used in fighting or
          hunting; "he was licensed to carry a weapon" [syn: {arm},
           {weapon system}]
     2: a means of persuading or arguing; "he used all his
        conversational weapons" [syn: {artillery}]