n. 1. light machine gun.
Syn. -- automatic rifle, machine rifle [ WordNet 1.5 ]

2. a pistol that will keep firing until the ammunition is gone or the trigger is released; as, a .45 automatic.
Syn. -- automatic pistol. [ WordNet 1.5 ]

{ } a. [ Cf. F. automatique. See Automaton. ] 1. Having an inherent power of action or motion. [ 1913 Webster ]

Nothing can be said to be automatic. Sir H. Davy. [ 1913 Webster ]

2. Pertaining to, or produced by, an automaton; of the nature of an automaton; self-acting or self-regulating under fixed conditions; operating with minimal human intervention; -- esp. applied to machinery or devices in which certain things formerly or usually done by hand are done by the machine or device itself; as, the automatic feed of a lathe; automatic gas lighting; an automatic engine or switch; an automatic mouse; an automatic transmission. The opposite of manual. Narrower terms are: autoloading(prenominal), semiautomatic ; automated, machine-controlled, machine-driven ; self-acting, self-activating, self-moving, self-regulating ; self-locking ; self-winding . Also See: mechanical. [ 1913 Webster + WordNet 1.5 ]

3. (Physiol.) Not voluntary; not depending on the will; mechanical; controlled by the autonomic nervous system; without conscious control; as, automatic movements or functions. The opposite of voluntary.
Syn. -- reflex(prenominal), reflexive, involuntary [ 1913 Webster + WordNet 1.5 ]

Unconscious or automatic reasoning. H. Spenser. [ 1913 Webster ]

4. like the unthinking functioning of a machine. an automatic `thank you'
Syn. -- automaton-like, automatonlike, machinelike, machine-like, robotlike. [ WordNet 1.5 ]

Automatic arts, such economic arts or manufacture as are carried on by self-acting machinery. Ure. [ 1913 Webster ]

adv. In an automatic manner. [ 1913 Webster ]

adj. same as hand-operated.
Syn. -- hand-operated. [ WordNet 1.5 +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. ]