(1) Of, relating to, associated with, or controlled by the autonomic nervous system
(2) Automatic, i.e. occurring spontaneously or involuntarily
The term autonomic is a descriptive word that generally pertains to being spontaneous or autonomous. In biology, autonomic is associated with the autonomic nervous system. For example, autonomic ganglia are ganglia of the autonomic nervous system located along the sympathetic trunks, on the peripheral plexuses, and the walls of the internal organs. Another example is autonomic nerve, which pertains to a bundle of nerve fibers associated with the autonomic nervous system.
The autonomic nervous system is part of the peripheral nervous system of vertebrates that is involved in involuntary muscle movements (as opposed to the other part of the peripheral nervous system, i.e. the somatic nervous system, which is involved in voluntary muscle movements). The autonomic nervous system primarily functions by supplying the stimulation from the motor nerves to the involuntary muscles and the glands of the body. It is comprised of two major divisions, the parasympathetic and the sympathetic nervous systems.
Word origin: Greek autos ("self") + nomos ("law")