adj

• (of a firearm such as a machine gun) Firing continuously as long as the trigger is pressed until ammunition is exhausted.
  "Fully automatic weapons cannot be legally owned by private citizens in the US, except in very special circumstances, as by private security companies."
• (of a handgun) An autoloader; a semi-automatic or self-loading pistol, as opposed to a revolver or other manually actuated handgun, which fires one shot per pull of the trigger; distinct from machine guns.
  "The US Army adopted John Browning's M1911 pistol as its sidearm, chambered in .45 ACP (Automatic Colt Pistol)."
• (programming, of a local variable) Automatically added to and removed from the stack during the course of function calls.
  "Automatic variables are created on the stack. They are valid only from the point where they are declared to the end of the function."
• (mathematics, of a group) Having one or more finite-state automata.