Source : Webster's Revised Unabridged Dictionary (1913)

Avatar \Av`a*tar"\, n. [Skr. avat[^a]ra descent; ava from + root
   t[.r] to cross, pass over.]
   1. (Hindoo Myth.) The descent of a deity to earth, and his
      incarnation as a man or an animal; -- chiefly associated
      with the incarnations of Vishnu.

   2. Incarnation; manifestation as an object of worship or
      admiration.

Source : WordNet®

avatar
     n 1: a new personification of a familiar idea; "the embodiment of
          hope"; "the incarnation of evil"; "the very avatar of
          cunning" [syn: {embodiment}, {incarnation}]
     2: the manifestation of a Hindu deity (especially Vishnu) in
        human or superhuman or animal form; "the Buddha is
        considered an avatar of the god Vishnu"

Source : Free On-Line Dictionary of Computing

avatar
     
        1.  An {image} representing a user in a
        multi-user {virtual reality} (or VR-like, in the case of
        {Palace}) space.
     
        2. (CMU, Tektronix) {root}, {superuser}.  There are quite a
        few {Unix} computers on which the name of the superuser
        account is "avatar" rather than "root".  This quirk was
        originated by a {CMU} hacker who disliked the term
        "superuser", and was propagated through an ex-CMU hacker at
        {Tektronix}.
     
        [{Jargon File}]
     
        (1997-09-14)