Having an inherent power of action or motion.  [1913 Webster]

 Pertaining to, or produced by, an automaton; of the nature of an automaton; self-acting or self-regulating under fixed conditions; operating with minimal human intervention; -- 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; an automatic transmission. The opposite of manual.

 Not voluntary; not depending on the will; mechanical; controlled by the autonomic nervous system; without conscious control; as, automatic movements or functions. The opposite of voluntary.  [1913 Webster]

 like the unthinking functioning of a machine.  [WordNet 1.5]