Source : Webster's Revised Unabridged Dictionary (1913)

Barium \Ba"ri*um\, n. [NL., fr. Gr. bary`s heavy.] (Chem.)
   One of the elements, belonging to the alkaline earth group; a
   metal having a silver-white color, and melting at a very high
   temperature. It is difficult to obtain the pure metal, from
   the facility with which it becomes oxidized in the air.
   Atomic weight, 137. Symbol, Ba. Its oxide called baryta.
   [Rarely written {barytum}.]

   Note: Some of the compounds of this element are remarkable
         for their high specific gravity, as the sulphate,
         called heavy spar, and the like. The oxide was called
         barote, by Guyton de Morveau, which name was changed by
         Lavoisier to baryta, whence the name of the metal.

Source : WordNet®

barium
     n : a soft silvery metallic element of the alkali earth group;
         found in barite [syn: {Ba}, {atomic number 56}]