<p><strong>Noun:</strong></p><ul><li>A nonmetallic element, having amorphous and crystalline forms, occurring in a combined state in minerals and rocks and constituting more than one fourth of the earth's crust.</li><li>Used in steelmaking, alloys, etc.</li><li>Chemical symbol: Si</li><li>Atomic weight: 28.086</li><li>Atomic number: 14</li><li>Density: 2.4 at 20°C</li></ul>