<p><strong>Noun</strong></p><ul><li>A steel-gray metallic element resembling tantalum in its chemical properties.</li><li>Becomes a superconductor below 9 K.</li><li>Used chiefly in alloy steels.</li><li>Symbol: Nb.</li><li>Atomic number: 41.</li><li>Atomic weight: 92.906.</li><li>Density: 8.4 at 20°C.</li></ul>