Adjective
Having an inherent power of action or motion.
Pertaining to, or produced by, an automaton; of the nature of an automaton; self-acting or self-regulating under fixed conditions; -- esp. applied to machinery or devices in which certain things formerly or usually done by hand are done by the machine or device itself; as, the automatic feed of a lathe; automatic gas lighting; an automatic engine or switch; an automatic mouse.
Not voluntary; not depending on the will; mechanical; as, automatic movements or functions.
Source: Webster's dictionary