The Collaborative International Dictionary of English v.0.48:

Cadmium \Cad"mi*um\, n. [NL. See Cadmia.] (Chem.)
   A comparatively rare element related to zinc, and occurring
   in some zinc ores. It is a white metal, both ductile and
   malleable. Symbol Cd. Atomic weight 111.8. It was discovered
   by Stromeyer in 1817, who named it from its association with
   zinc or zinc ore.
   [1913 Webster]

   Cadmium yellow, a compound of cadmium and sulphur, of an
      intense yellow color, used as a pigment.
      [1913 Webster]

WordNet (r) 3.0 (2006):

cadmium
    n 1: a soft bluish-white ductile malleable toxic bivalent
         metallic element; occurs in association with zinc ores
         [syn: cadmium, Cd, atomic number 48]