/oz"mee euhm/ , n. Chem.
a hard, heavy, metallic element having the greatest density of the known elements and forming octavalent compounds, as OsO 4 and OsF 8 : used chiefly as a catalyst, in alloys, and in the manufacture of electric-light filaments. Symbol: Os; at. wt.: 190.2; at. no.: 76; sp. gr.: 22.57.
[ 1795-1805; osm ( é ) smell + -ium -IUM; named from the penetrating odor of one of its oxides ]