NOUN (1)

1. a rapidly firing automatic gun (often mounted);


VERB (1)

1. shoot with a machine gun;

The Collaborative International Dictionary of English v.0.48:

Gun \Gun\ (g[u^]n), n. [OE. gonne, gunne; of uncertain origin;
   cf. Ir., Gael., & LL. gunna, W. gum; possibly (like cannon)
   fr. L. canna reed, tube; or abbreviated fr. OF. mangonnel, E.
   mangonel, a machine for hurling stones.]
   1. A weapon which throws or propels a missile to a distance;
      any firearm or instrument for throwing projectiles,
      consisting of a tube or barrel closed at one end, in which
      the projectile is placed, with an explosive charge (such
      as guncotton or gunpowder) behind, which is ignited by
      various means. Pistols, rifles, carbines, muskets, and
      fowling pieces are smaller guns, for hand use, and are
      called small arms. Larger guns are called cannon,
      ordnance, fieldpieces, carronades, howitzers, etc.
      See these terms in the Vocabulary.
      [1913 Webster]

            As swift as a pellet out of a gunne
            When fire is in the powder runne.     --Chaucer.
      [1913 Webster]

            The word gun was in use in England for an engine to
            cast a thing from a man long before there was any
            gunpowder found out.                  --Selden.
      [1913 Webster]

   2. (Mil.) A piece of heavy ordnance; in a restricted sense, a
      cannon.
      [1913 Webster]

   3. pl. (Naut.) Violent blasts of wind.
      [1913 Webster]

   Note: Guns are classified, according to their construction or
         manner of loading as rifled or smoothbore,
         breech-loading or muzzle-loading, cast or
         built-up guns; or according to their use, as field,
         mountain, prairie, seacoast, and siege guns.
         [1913 Webster]

   Armstrong gun, a wrought iron breech-loading cannon named
      after its English inventor, Sir William Armstrong.

   Big gun or Great gun, a piece of heavy ordnance; hence
      (Fig.), a person superior in any way; as, bring in the big
      guns to tackle the problem.

   Gun barrel, the barrel or tube of a gun.

   Gun carriage, the carriage on which a gun is mounted or
      moved.

   Gun cotton (Chem.), a general name for a series of
      explosive nitric ethers of cellulose, obtained by steeping
      cotton in nitric and sulphuric acids. Although there are
      formed substances containing nitric acid radicals, yet the
      results exactly resemble ordinary cotton in appearance. It
      burns without ash, with explosion if confined, but quietly
      and harmlessly if free and open, and in small quantity.
      Specifically, the lower nitrates of cellulose which are
      insoluble in ether and alcohol in distinction from the
      highest (pyroxylin) which is soluble. See Pyroxylin, and
      cf. Xyloidin. The gun cottons are used for blasting and
      somewhat in gunnery: for making celluloid when compounded
      with camphor; and the soluble variety (pyroxylin) for
      making collodion. See Celluloid, and Collodion. Gun
      cotton is frequenty but improperly called
      nitrocellulose. It is not a nitro compound, but an ester
      of nitric acid.

   Gun deck. See under Deck.

   Gun fire, the time at which the morning or the evening gun
      is fired.

   Gun metal, a bronze, ordinarily composed of nine parts of
      copper and one of tin, used for cannon, etc. The name is
      also given to certain strong mixtures of cast iron.

   Gun port (Naut.), an opening in a ship through which a
      cannon's muzzle is run out for firing.

   Gun tackle (Naut.), the blocks and pulleys affixed to the
      side of a ship, by which a gun carriage is run to and from
      the gun port.

   Gun tackle purchase (Naut.), a tackle composed of two
      single blocks and a fall. --Totten.

   Krupp gun, a wrought steel breech-loading cannon, named
      after its German inventor, Herr Krupp.

   Machine gun, a breech-loading gun or a group of such guns,
      mounted on a carriage or other holder, and having a
      reservoir containing cartridges which are loaded into the
      gun or guns and fired in rapid succession. In earlier
      models, such as the Gatling gun, the cartridges were
      loaded by machinery operated by turning a crank. In modern
      versions the loading of cartidges is accomplished by
      levers operated by the recoil of the explosion driving the
      bullet, or by the pressure of gas within the barrel.
      Several hundred shots can be fired in a minute by such
      weapons, with accurate aim. The Gatling gun, Gardner
      gun, Hotchkiss gun, and Nordenfelt gun, named for
      their inventors, and the French mitrailleuse, are
      machine guns.

   To blow great guns (Naut.), to blow a gale. See Gun, n.,
      3.
      [1913 Webster +PJC]

The Collaborative International Dictionary of English v.0.48:

Machine \Ma*chine"\ (m[.a]*sh[=e]n"), n. [F., fr. L. machina
   machine, engine, device, trick, Gr. mhchanh`, from mh^chos
   means, expedient. Cf. Mechanic.]
   1. In general, any combination of bodies so connected that
      their relative motions are constrained, and by means of
      which force and motion may be transmitted and modified, as
      a screw and its nut, or a lever arranged to turn about a
      fulcrum or a pulley about its pivot, etc.; especially, a
      construction, more or less complex, consisting of a
      combination of moving parts, or simple mechanical
      elements, as wheels, levers, cams, etc., with their
      supports and connecting framework, calculated to
      constitute a prime mover, or to receive force and motion
      from a prime mover or from another machine, and transmit,
      modify, and apply them to the production of some desired
      mechanical effect or work, as weaving by a loom, or the
      excitation of electricity by an electrical machine.
      [1913 Webster]

   Note: The term machine is most commonly applied to such
         pieces of mechanism as are used in the industrial arts,
         for mechanically shaping, dressing, and combining
         materials for various purposes, as in the manufacture
         of cloth, etc. Where the effect is chemical, or other
         than mechanical, the contrivance is usually denominated
         an apparatus or device, not a machine; as, a bleaching
         apparatus. Many large, powerful, or specially important
         pieces of mechanism are called engines; as, a steam
         engine, fire engine, graduating engine, etc. Although
         there is no well-settled distinction between the terms
         engine and machine among practical men, there is a
         tendency to restrict the application of the former to
         contrivances in which the operating part is not
         distinct from the motor.
         [1913 Webster]

   2. Any mechanical contrivance, as the wooden horse with which
      the Greeks entered Troy; a coach; a bicycle. --Dryden.
      --Southey. --Thackeray.
      [1913 Webster]

   3. A person who acts mechanically or at the will of another.
      [1913 Webster]

   4. A combination of persons acting together for a common
      purpose, with the agencies which they use; as, the social
      machine.
      [1913 Webster]

            The whole machine of government ought not to bear
            upon the people with a weight so heavy and
            oppressive.                           --Landor.
      [1913 Webster]

   5. A political organization arranged and controlled by one or
      more leaders for selfish, private or partisan ends; the
      Tammany machine. [Political Cant]
      [1913 Webster]

   6. Supernatural agency in a poem, or a superhuman being
      introduced to perform some exploit. --Addison.
      [1913 Webster]

   Elementary machine, a name sometimes given to one of the
      simple mechanical powers. See under Mechanical.

   Infernal machine. See under Infernal.

   Machine gun.See under Gun.

   Machine screw, a screw or bolt adapted for screwing into
      metal, in distinction from one which is designed
      especially to be screwed into wood.

   Machine shop, a workshop where machines are made, or where
      metal is shaped by cutting, filing, turning, etc.

   Machine tool, a machine for cutting or shaping wood, metal,
      etc., by means of a tool; especially, a machine, as a
      lathe, planer, drilling machine, etc., designed for a more
      or less general use in a machine shop, in distinction from
      a machine for producing a special article as in
      manufacturing.

   Machine twist, silken thread especially adapted for use in
      a sewing machine.

   Machine work, work done by a machine, in contradistinction
      to that done by hand labor.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

machine gun \machine gun\ n.
   A fully automatic rapid-firing rifle, which continues to fire
   bullets repeatedly as long as the trigger is depressed;
   lighter versions may be carried in the hands, and heavier
   versions may be mounted on a tripod, vehicle, or other mount.
   The lighweight versions are sometimes called a submachine
   gun.
   [PJC] machine-gun

The Collaborative International Dictionary of English v.0.48:

machine-gun \machine-gun\, machine gun \machine gun\a.
   Occurring in rapid succession, like the firing of a machine
   gun; as, Tom was a persuasive speaker, with a smooth deep
   voice, polysyllabic vocabulary, and a machine-gun
   articulation that overwhelmed listeners.

   Syn: rapid-fire.
        [PJC]

WordNet (r) 3.0 (2006):

machine gun
    n 1: a rapidly firing automatic gun (often mounted)
    v 1: shoot with a machine gun