\Pal*la"di*um\, n. [L., fr. Gr. ?, fr. ?, ?, Pallas.]
1. (Gr. Antiq.) Any statue of the goddess Pallas; esp., the
   famous statue on the preservation of which depended the
   safety of ancient Troy.
2. Hence: That which affords effectual protection or
   security; a sateguard; as, the trial by jury is the
   palladium of our civil rights. --Blackstone.

\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. It is
unique in its power of occluding 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 weight,
106.2.