Plu·to pr. n.
 1. Class. Myth. The son of Saturn and Rhea, brother of Jupiter and Neptune; the dark and gloomy god of the Lower World.
    Pluto is an oddball among its eight sister planets.  It's the smallest in both size and mass, and has the most elliptical orbit.  It moves in a plane tilted markedly away from the other planets' orbits.  Moreover, Pluto is the only planet made almost entirely of ice.    --Ron Cohen (Science News, Feb. 27, 1999, p. 139)
 Pluto monkey Zool., a long-tailed African monkey (Cercopithecus pluto), having side whiskers.  The general color is black, more or less grizzled; the frontal band is white.
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