Source : Webster's Revised Unabridged Dictionary (1913)

Yellow \Yel"low\, n.
   1. A bright golden color, reflecting more light than any
      other except white; the color of that part of the spectrum
      which is between the orange and green. ``A long motley
      coat guarded with yellow.'' --Shak.

   2. A yellow pigment.

   {Cadmium yellow}, {Chrome yellow}, {Indigo yellow}, {King's
   yellow}, etc. See under {Cadmium}, {Chrome}, etc.

   {Naples yellow}, a yellow amorphous pigment, used in oil,
      porcelain, and enamel painting, consisting of a basic lead
      metantimonate, obtained by fusing together tartar emetic
      lead nitrate, and common salt.

   {Patent yellow} (Old Chem.), a yellow pigment consisting
      essentially of a lead oxychloride; -- called also
      {Turner's yellow}.

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.

   {Cadmium yellow}, a compound of cadmium and sulphur, of an
      intense yellow color, used as a pigment.

Source : WordNet®

cadmium yellow
     n : pigment of cadmium sulfide and barium sulfate varying in hue
         from lemon yellow to orange