The Collaborative International Dictionary of English v.0.48:

National \Na"tion*al\ (?; 277), a. [Cf. F. national.]
   1. Of or pertaining to a nation; common to a whole people or
      race; public; general; as, a national government,
      language, dress, custom, calamity, etc.
      [1913 Webster]

   2. Attached to one's own country or nation.
      [1913 Webster]

   National anthem, a popular song or hymn which has become by
      general acceptance the recognized musical expression of
      the patriotic sentiment of a nation; as, "God save the
      King" is called the national anthem of England.

   National bank, the official common name of a class of
      banking corporations established under the laws of the
      United States.

   National flag. See under Flag.

   National guard, a body of militia, or a local military
      organization, as in Paris during the French Revolution, or
      as certain bodies of militia in other European countries
      and in the United States.

   National salute, a salute consisting of as many guns as
      there are States in the Union. [U.S.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

national anthem
    n 1: a song formally adopted as the anthem for a nation

Moby Thesaurus II by Grady Ward, 1.0:

72 Moby Thesaurus words for "national anthem":
   Brautlied, Christmas carol, Communist threat, Kunstlied,
   Liebeslied, Volkslied, Western imperialism, alba, anthem, art song,
   atrocity story, aubade, ballad, ballade, ballata, banner,
   barcarole, battle hymn, bloody shirt, blues, blues song, boat song,
   bridal hymn, brindisi, calypso, canso, canticle, canzone, canzonet,
   canzonetta, carol, cavatina, chanson, chant, chantey, colors,
   croon, croon song, crostarie, dirge, ditty, drinking song,
   epithalamium, expansionism, face, fiery cross, folk song, gonfalon,
   hymeneal, imperialist threat, independence, lay, lied, lilt,
   love song, love-lilt, manifest destiny, martial music, matin,
   minstrel song, minstrelsy, prothalamium, self-determination,
   serena, serenade, serenata, song, theme song, torch song, war song,
   wedding song, yellow peril