The Collaborative International Dictionary of English v.0.48:

Palladium \Pal*la"di*um\, n. [NL.] (Chem.)
   A rare metallic element of the light platinum group, found
   native, and also alloyed with platinum and gold. It is a
   silver-white metal resembling platinum, and like it permanent
   and untarnished in the air, but is more easily fusible, with
   a melting point of 1555[deg] C. It can also be prepared as a
   finely divided black powder. It is unique in its power of
   absorbing hydrogen, which it does to the extent of nearly a
   thousand volumes, forming the alloy Pd2H. It is used for
   graduated circles and verniers, for plating certain silver
   goods, and somewhat in dentistry. It was so named in 1804 by
   Wollaston from the asteroid Pallas, which was discovered in
   1802. Symbol Pd. Atomic number, 46. Atomic weight, 106.42.
   Density 12.0.
   [1913 Webster]