automatic —adj.
1 working by itself, without direct human intervention.
2 a done spontaneously (automatic reaction). b following inevitably (automatic penalty).
3 (of a firearm) able to be loaded and fired continuously.
4 (of a vehicle or its transmission) using gears that change automatically. —n.

Example

1 automatic machine, firearm, or tool.
2 vehicle with automatic transmission.  automatically adv.