The Collaborative International Dictionary of English v.0.48:

Swan \Swan\ (sw[o^]n), n. [AS. swan; akin to D. zwaan, OHG.
   swan, G. schwan, Icel. svanr, Sw. svan, Dan. svane; and
   perhaps to E. sound something audible.]
   1. (Zool.) Any one of numerous species of large aquatic birds
      belonging to Cygnus, Olor, and allied genera of the
      subfamily Cygninae. They have a large and strong beak
      and a long neck, and are noted for their graceful
      movements when swimming. Most of the northern species are
      white. In literature the swan was fabled to sing a
      melodious song, especially at the time of its death.
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   Note: The European white, or mute, swan (Cygnus gibbus),
         which is most commonly domesticated, bends its neck in
         an S-shaped curve. The whistling, or trumpeting, swans
         of the genus Olor do not bend the neck in an S-shaped
         curve, and are noted for their loud and sonorous cry,
         due to complex convolutions of the windpipe. To this
         genus belong the European whooper, or whistling swan
         (Olor cygnus), the American whistling swan (Olor
         Columbianus), and the trumpeter swan (Olor
         buccinator). The Australian black swan (Chenopis
         atrata) is dull black with white on the wings, and has
         the bill carmine, crossed with a white band. It is a
         very graceful species and is often domesticated. The
         South American black-necked swan (Sthenelides
         melancorypha) is a very beautiful and graceful
         species, entirely white, except the head and neck,
         which are dark velvety seal-brown. Its bill has a
         double bright rose-colored knob.
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   2. Fig.: An appellation for a sweet singer, or a poet noted
      for grace and melody; as Shakespeare is called the swan of
      Avon.
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   3. (Astron.) The constellation Cygnus.
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   Swan goose (Zool.), a bird of India (Cygnopsis cygnoides)
      resembling both the swan and the goose.

   Swan shot, a large size of shot used in fowling.
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