Source : Webster's Revised Unabridged Dictionary (1913)

Hydrargyrum \Hy*drar"gy*rum\, n. [NL., fr. L. hydrargyrus, Gr.
   ?; ? water + ? silver.] (Chem.)
   Quicksilver; mercury.

Source : WordNet®

hydrargyrum
     n : a heavy silvery toxic univalent and bivalent metallic
         element; the only metal that is liquid at ordinary
         temperatures [syn: {mercury}, {quicksilver}, {Hg}, {atomic
         number 80}]