Synonyms for Automatic:

adj.

done by habit (adjective)
reflex, unforced, intuitive, unintentional, involuntary, perfunctory, unconscious, habitual, unthinking.
done or made by machine (adjective)
electric, electronic, self-moving, self-regulating, mechanical, motorized, automated.
habitual (adjective)
premeditated, unforced, habitual, unintentional, intuitive, mechanical, unconscious, deliberate, unthinking.

n.

arbitrary, coincidental, unintended, by accident, impromptu, random, accidental. by virtue of something, accordingly, as a consequence/in consequence, therefore, planned, thus, knock on, unpremeditated, ensuing, From, consequently, hence. 045, air gun, air rifle, concern, carbine, derringer, cannon, mechanical, bb gun, perfunctory, bazooka, blunderbuss. built, clever, automatically, clockwork, auxiliary, broken, clean, analog, cordless. loaded, Rapid-fire, double-barreled. cruiser, estate, compact, dragster, convertible, coupe, demo, cabriolet, classic car. artifact (noun)
automatic rifle, machine rifle.
automatic (noun)
self-acting, self-moving, machine-controlled, self-winding, semiautomatic, self-locking, robotlike, automatonlike, self-activating, automatic rifle, self-loading, reflex, automatic pistol, automated, involuntary, machine-driven, machine rifle, autoloading, machinelike, reflexive, self-regulating.
habitual (noun)
mechanical, unintended, unthinking, reflexive, involuntary, intuitive, unintentional, habitual, reflex, unconscious, unforced.

Other synonyms:

cabriolet, bazooka, cannon, air gun, cordless, intuitive, blunderbuss, loaded, habitual, air rifle, built, derringer, Rapid-fire, classic car, bb gun, coupe, carbine. compact, broken, cruiser, motorized, convertible, double-barreled, unpremeditated, analog, perfunctory, automatically. auxiliary, electric. clever, demo. estate. mechanical
mechanical, reflex.
photoelectric
electronic.

Usage examples for automatic

  1. He felt the automatic pistol and the ammunition being removed from his pockets. – The Pygmy Planet by John Stewart Williamson
  2. At his approach, she paused in her task and stood waiting for him, with the expression of interested, if automatic attention, which appeared on her face, as in answer to some secret spring, whenever she was invited to perform the delicate part of a listener. – The Miller Of Old Church by Ellen Glasgow
  3. Across the face of one of the buildings there was an enormous sign: " Sheridan Automatic Pump Co. – The Turmoil A Novel by Booth Tarkington