Source : Webster's Revised Unabridged Dictionary (1913)

Nickname \Nick"name`\, n. [OE. ekename surname, hence, a
   nickname, an ekename being understood as a nekename,
   influenced also by E. nick, v. See {Eke}, and {Name}.]
   A name given in contempt, derision, or sportive familiarity;
   a familiar or an opprobrious appellation.

Nickname \Nick"name`\, v. t. [imp. & p. p. {Nicknamed}; p. pr. &
   vb. n. {Nicknaming}.]
   To give a nickname to; to call by a nickname.

         You nickname virtue; vice you should have spoke.
                                                  --Shak.

         I altogether disclaim what has been nicknamed the
         doctrine of finality.                    --Macaulay.

Source : WordNet®

nickname
     n 1: a familiar name  for a person (often a shortened version of
          a person's given name); "Joe's mother would not use his
          nickname and always called him Joseph"; "Henry's
          nickname was Slim" [syn: {moniker}, {cognomen}, {sobriquet},
           {soubriquet}]
     2: a descriptive name for a place or thing; "the nickname for
        the U.S. Constitution is `Old Ironsides'"
     v : give a nickname to [syn: {dub}]