Source : Webster's Revised Unabridged Dictionary (1913)

Pluto \Plu"to\, n. [L., fr. Gr. ?.] (Class. Myth.)
   The son of Saturn and Rhea, brother of Jupiter and Neptune;
   the dark and gloomy god of the Lower World.

   {Pluto monkey} (Zo["o]l.), a long-tailed African monkey
      ({Cercopithecus pluto}), having side whiskers. The general
      color is black, more or less grizzled; the frontal band is
      white.