Acting or operating in a manner essentially independent of external influence or control: an automatic light switch; a budget deficit that triggered automatic spending cuts. Self-regulating: an automatic washing machine. Acting or done without volition or conscious control; involuntary: automatic shrinking of the pupils of the eyes in strong light. See Synonyms at spontaneous. Acting or done as if by machine; mechanical: an automatic reply to a familiar question. Capable of firing continuously until ammunition is exhausted or the trigger is released: an automatic rifle. Semiautomatic: an automatic pistol. An automatic machine or device. An automatic firearm. A semiautomatic firearm. A transmission or a motor vehicle with an automatic gear-shifting mechanism. Football See audible. on automatic Functioning by or as if by automatic machine or device.