Source : Webster's Revised Unabridged Dictionary (1913)

Swan \Swan\, 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. (Zo["o]l.) Any one of numerous species of large aquatic
      birds belonging to {Cygnus}, {Olor}, and allied genera of
      the subfamily {Cygnin[ae]}. 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.

   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 ({O.
         Columbianus}), and the trumpeter swan ({O.
         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.

   2. Fig.: An appellation for a sweet singer, or a poet noted
      for grace and melody; as Shakespeare is called the swan of
      Avon.

   3. (Astron.) The constellation Cygnus.

   {Swan goose} (Zo["o]l.), a bird of India ({Cygnopsis
      cygnoides}) resembling both the swan and the goose.

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

Source : WordNet®

swan
     n : stately heavy-bodied aquatic bird with very long neck and
         usually white plumage as adult

swan
     v 1: to declare or affirm solemnly and formally as true; "Before
          God I swear I am innocent" [syn: {affirm}, {verify}, {assert},
           {avow}, {aver}, {swear}]
     2: move about aimlessly or without any destination, often in
        search of food or employment; "The gypsies roamed the
        woods"; "roving vagabonds"; "the wandering Jew"; "The
        cattle roam across the prairie"; "the laborers drift from
        one town to the next"; "They rolled from town to town"
        [syn: {roll}, {wander}, {stray}, {tramp}, {roam}, {cast},
        {ramble}, {rove}, {range}, {drift}, {vagabond}]
     3: sweep majestically; "Airplanes were swanning over the
        mountains"