Source : Webster's Revised Unabridged Dictionary (1913)

Calcium \Cal"ci*um\ (k[a^]l"s[i^]*[u^]m), n. [NL., from L. calx,
   calcis, lime; cf F. calcium. See {Calx}.] (Chem.)
   An elementary substance; a metal which combined with oxygen
   forms lime. It is of a pale yellow color, tenacious, and
   malleable. It is a member of the alkaline earth group of
   elements. Atomic weight 40. Symbol Ca.

   Note: Calcium is widely and abundantly disseminated, as in
         its compounds calcium carbonate or limestone, calcium
         sulphate or gypsum, calcium fluoride or fluor spar,
         calcium phosphate or apatite.

   {Calcium light}, an intense light produced by the
      incandescence of a stick or ball of lime in the flame of a
      combination of oxygen and hydrogen gases, or of oxygen and
      coal gas; -- called also {Drummond light}.

Source : WordNet®

calcium
     n : a white metallic element that burns with a brilliant light;
         the fifth most abundant element in the earth's crust; an
         important component of most plants and animals [syn: {Ca},
          {atomic number 20}]