Source : Webster's Revised Unabridged Dictionary (1913)

Tellurium \Tel*lu"ri*um\, n. [NL., from L. tellus, -uris, the
   earth.] (Chem.)
   A rare nonmetallic element, analogous to sulphur and
   selenium, occasionally found native as a substance of a
   silver-white metallic luster, but usually combined with
   metals, as with gold and silver in the mineral sylvanite,
   with mercury in Coloradoite, etc. Symbol Te. Atomic weight
   125.2.

   {Graphic tellurium}. (Min.) See {Sylvanite}.

   {Tellurium glance} (Min.), nagyagite; -- called also {black
      tellurium}.

Source : WordNet®

tellurium
     n : a brittle silver-white metalloid element that is related to
         selenium and sulfur; it is used in alloys and as a
         semiconductor; occurs mainly as tellurides in ores of
         copper and nickel and silver and gold [syn: {Te}, {atomic
         number 52}]