Source : Webster's Revised Unabridged Dictionary (1913)

Beryllium \Be*ryl"li*um\, n. [NL.] (Chem.)
   A metallic element found in the beryl. See {Glucinum}.

Source : WordNet®

beryllium
     n : a light strong brittle gray toxic bivalent metallic element
         [syn: {Be}, {glucinium}, {atomic number 4}]