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 Guard
    n 1: United States military reserves recruited by the states and
         equipped by the federal government; subject to call by
         either [syn: National Guard, home reserve]