NOUN (2)

1. a giant planet that is surrounded by three planar concentric rings of ice particles; the 6th planet from the sun;

2. (Roman mythology) god of agriculture and vegetation; counterpart of Greek Cronus;
- Example: "Saturday is Saturn's Day"

The Collaborative International Dictionary of English v.0.48:

Saturn \Sa"turn\, n. [L. Saturnus, literally, the sower, fr.
   serere, satum, to sow. See Season.]
   1. (Roman Myth.) One of the elder and principal deities, the
      son of Coelus and Terra (Heaven and Earth), and the father
      of Jupiter. The corresponding Greek divinity was Kro`nos,
      later CHro`nos, Time.
      [1913 Webster]

   2. (Astron.) One of the planets of the solar system, next in
      magnitude to Jupiter, but more remote from the sun. Its
      diameter is seventy thousand miles, its mean distance from
      the sun nearly eight hundred and eighty millions of miles,
      and its year, or periodical revolution round the sun,
      nearly twenty-nine years and a half. It is surrounded by a
      remarkable system of rings, and has eight satellites.
      [1913 Webster]

   3. (Alchem.) The metal lead. [Archaic]
      [1913 Webster]

WordNet (r) 3.0 (2006):

Saturn
    n 1: a giant planet that is surrounded by three planar
         concentric rings of ice particles; the 6th planet from the
         sun
    2: (Roman mythology) god of agriculture and vegetation;
       counterpart of Greek Cronus; "Saturday is Saturn's Day"