osmium: Meaning and Definition of

os•mi•um

1. a hard, heavy, metallic element having the greatest density of the known elements and forming octavalent compounds, as OsO and OsF: 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.