资料来源 : Webster's Revised Unabridged Dictionary (1913)

Na \Na\ (n[aum]), a. & adv.
   No, not. See {No}. [Obs.] --Chaucer.

Symbol \Sym"bol\, n. [L. symbolus, symbolum, Gr. sy`mbolon a
   sign by which one knows or infers a thing, from ? to throw or
   put together, to compare; sy`n with + ? to throw: cf. F.
   symbole. Cf. {Emblem}, {Parable}.]
   1. A visible sign or representation of an idea; anything
      which suggests an idea or quality, or another thing, as by
      resemblance or by convention; an emblem; a representation;
      a type; a figure; as, the lion is the symbol of courage;
      the lamb is the symbol of meekness or patience.

            A symbol is a sign included in the idea which it
            represents, e. g., an actual part chosen to
            represent the whole, or a lower form or species used
            as the representative of a higher in the same kind.
                                                  --Coleridge.

   2. (Math.) Any character used to represent a quantity, an
      operation, a relation, or an abbreviation.

   Note: In crystallography, the symbol of a plane is the
         numerical expression which defines its position
         relatively to the assumed axes.

   3. (Theol.) An abstract or compendium of faith or doctrine; a
      creed, or a summary of the articles of religion.

   4. [Gr. ? contributions.] That which is thrown into a common
      fund; hence, an appointed or accustomed duty. [Obs.]

            They do their work in the days of peace . . . and
            come to pay their symbol in a war or in a plague.
                                                  --Jer. Taylor.

   5. Share; allotment. [Obs.]

            The persons who are to be judged . . . shall all
            appear to receive their symbol.       --Jer. Taylor.

   6. (Chem.) An abbreviation standing for the name of an
      element and consisting of the initial letter of the Latin
      or New Latin name, or sometimes of the initial letter with
      a following one; as, {C} for carbon, {Na} for sodium
      (Natrium), {Fe} for iron (Ferrum), {Sn} for tin (Stannum),
      {Sb} for antimony (Stibium), etc. See the list of names
      and symbols under {Element}.

   Note: In pure and organic chemistry there are symbols not
         only for the elements, but also for their grouping in
         formulas, radicals, or residues, as evidenced by their
         composition, reactions, synthesis, etc. See the diagram
         of {Benzene nucleus}, under {Benzene}.

   Syn: Emblem; figure; type. See {Emblem}.

资料来源 : WordNet®

Na
     n : a silvery soft waxy metallic element of the alkali metal
         group; occurs abundantly in natural compounds (especially
         in salt water); burns with a yellow flame and reacts
         violently in water; occurs in sea water and in the
         mineral halite (rock salt) [syn: {sodium}, {atomic number
         11}]

资料来源 : Free On-Line Dictionary of Computing

na
     
         The {country code} for Namibia.
     
        (1999-01-27)