Source : Webster's Revised Unabridged Dictionary (1913)

Jupiter \Ju"pi*ter\, n. [L., fr. Jovis pater. See {Jove}.]
   1. (Rom. Myth.) The supreme deity, king of gods and men, and
      reputed to be the son of Saturn and Rhea; Jove. He
      corresponds to the Greek Zeus.

   2. (Astron.) One of the planets, being the brightest except
      Venus, and the largest of them all, its mean diameter
      being about 85,000 miles. It revolves about the sun in
      4,332.6 days, at a mean distance of 5.2028 from the sun,
      the earth's mean distance being taken as unity.

   {Jupiter's beard}. (Bot.)
      (a) A South European herb, with cymes of small red
          blossoms ({Centranthus ruber}).
      (b) The houseleek ({Sempervivum tectorum}); -- so called
          from its massive inflorescence, like the sculptured
          beard of Jove. --Prior.
      (c) the cloverlike {Anthyllis Barba-Jovis}.

   {Jupiter's staff} (Bot.), the common mullein; -- so called
      from its long, rigid spike of yellow blossoms.

Source : WordNet®

Jupiter
     n 1: the largest planet and the 5th from the sun; has many
          satellites
     2: (Roman mythology) supreme god of Romans; counterpart of
        Greek Zeus [syn: {Jove}]

Source : Free On-Line Dictionary of Computing

jupiter
     
        To kill an {IRC} {robot} or user and then take its place by
        adopting its {nick} so that it cannot reconnect.  Named after
        a particular IRC user who did this to {NickServ}, the robot in
        charge of preventing people from inadvertently using a nick
        claimed by another user.
     
        [{Jargon File}]
     
        (1994-11-23)