<p><strong>noun</strong></p><ul><li>Chemistry, Physics: A transuranic element with a fissile isotope of mass number 239 (plutonium-239) that can be produced from non-fissile uranium-238, as in a breeder reactor.</li><li>Symbol: Pu</li><li>Atomic number: 94</li></ul><p><strong>End of Response</strong></p>