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]

The Elements (07Nov00):

cadmium
Symbol: Cd
Atomic number: 48
Atomic weight: 112.40
Soft bluish metal belonging to group 12 of the periodic table. Extremely
toxic even in low concentrations. Chemically similar to zinc, but lends
itself to more complex compounds. Discovered in 1817 by F. Stromeyer.