General English

General Science

  • adjective working by itself without the need of an operator


  • adjective working or taking place without any person making it happen

Cars & Driving


  • Descriptive of any device activated by the environment or a predetermined condition, such as a ventilator that opens at a given temperature.


  • A component, device, system, or process which does not require intervention, human or otherwise. It may have self-acting and/or self-regulating mechanisms, and utilize an autonomous information processing system. Also, pertaining to any such component, device, system, or process.

Information & Library Science

  • adjective able to operate by itself without constant user input


  • adjective done without conscious thought
  • adjective able to work by itself, without anyone giving instructions


  • noun a firearm which will continue to reload itself and fire for as long as pressure is applied to the trigger (e.g. a machine-gun)