Definitions of automatic:

• noun:   a pistol that will keep firing until the ammunition is gone or the trigger is released
• noun:   light machine gun
• adjective:   like the unthinking functioning of a machine

  Example: "An automatic `thank you'"

• adjective:   without volition or conscious control

  Example: "The automatic shrinking of the pupils of the eye in strong light"

• adjective:   operating with minimal human intervention; independent of external control

  Example: "Automatic transmission"