Source : Webster's Revised Unabridged Dictionary (1913)

Autonomous \Au*ton"o*mous\, a. [Gr. ?; ? self + ? to assign,
   hold, sway.]
   1. Independent in government; having the right or power of
      self-government.

   2. (Biol.) Having independent existence or laws.

Source : WordNet®

autonomous
     adj 1: of political bodies; "an autonomous judiciary"; "a sovereign
            state" [syn: {independent}, {self-governing}, {sovereign}]
     2: existing as an independent entity; "the partitioning of
        India created two separate and autonomous jute economies"
     3: of persons; free from external control and constraint in
        e.g. action and judgment [syn: {self-directed}, {self-reliant}]