of a machine or device : having controls that allow something to work or happen without being directly controlled by a person
of a gun : shooting many bullets very quickly when the trigger is pulled
: happening or done without deliberate thought or effort
: a gun that shoots many bullets very quickly : an automatic weapon
: a vehicle that changes gears by itself at different speeds : a car with automatic transmission
What made you want to look up automatic? Please tell us where you read or heard it (including the quote, if possible).