Auto.

Capable of operating without external control or intervention.

"The automatic clothes washer was a great labor-saving device."

Done out of habit or without conscious thought.

"Absent-minded doodling is a form of automatic art."

Necessary, inevitable, prescribed by logic, law, etc.

"Spitting at another player means an automatic red card."

(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."