Definition of "plutonium" []

• A naturally radioactive, silvery, metallic transuranic element, occurring in uranium ores and produced artificially by neutron bombardment of uranium. Its longest-lived isotope is Pu 244 with a half-life of 76 million years. It is a radiological poison, specifically absorbed by bone marrow, and is used, especially the highly fissionable isotope Pu 239, as a reactor fuel and in nuclear weapons. Atomic number 94; melting point 640°C; boiling point 3,235°C; specific gravity 19.84; valence 3, 4, 5, 6. See Table at element. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "“I'm sure that in 1985 plutonium is available in every corner drugstore, but in 1955 it's a little hard to come by.”"
• "In 2007, North Korea shut down its main plutonium-producing plant and agreed to end all nuclear programs in exchange for aid and diplomatic concessions."
• "The half-life of (radioactive) plutonium is about 77,000 years."