What is the meaning of automatic?

noun

• Light machine gun.
  • synonyms: automatic rifle, machine rifle
• A pistol that will keep firing until the ammunition is gone or the trigger is released.
  • synonyms: automatic pistol

adjective

• Operating with minimal human intervention; independent of external control.
  • usage: "automatic transmission"; "a budget deficit that caused automatic spending cuts"
• Resembling the unthinking functioning of a machine.
  • usage: "an automatic `thank you'"; "machinelike efficiency"
  • synonyms: automatonlike, machinelike, robotlike, robotic
• Without volition or conscious control.
  • usage: "the automatic shrinking of the pupils of the eye in strong light"; "a reflex knee jerk"; "sneezing is reflexive"
  • synonyms: reflex, reflexive