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 ]

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 ]

n. A soldier who operates a machine gun. [ PJC ]

. An automatic machine gun in which the mechanism is worked by the recoil, assisted by the pressure of gases from the muzzle, which expand in a gas chamber against a disk attached to the end of the barrel, thus moving the latter to the rear with increased recoil, and against the front wall of the gas chamber, checking the recoil of the system. [ Webster 1913 Suppl. ]