<p><strong>Noun</strong></p><ul><li>Chemistry</li><li>A hard, heavy, metallic element</li><li>Having the greatest density of the known elements</li><li>Forms octavalent compounds, such as OsO₄ and OsF₈</li><li>Used chiefly as a catalyst, in alloys, and in the manufacture of electric-light filaments</li><li>Symbol: Os</li><li>Atomic weight: 190.2</li><li>Atomic number: 76</li><li>Density: 22.57</li></ul>