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plutonium

[ploo-toh-nee-uh m] /pluˈtoʊ ni əm/
noun, Chemistry, Physics.
1.
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. Symbol: Pu; atomic number: 94.
Origin
1940-1945
1940-45; < Greek Ploútōn Pluto + -ium
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Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for plutonium 239

plutonium

/pluːˈtəʊnɪəm/
noun
1.
a highly toxic metallic transuranic element. It occurs in trace amounts in uranium ores and is produced in a nuclear reactor by neutron bombardment of uranium-238. The most stable and important isotope, plutonium-239, readily undergoes fission and is used as a reactor fuel in nuclear power stations and in nuclear weapons. Symbol: Pu; atomic no: 94; half-life of 239Pu: 24 360 years; valency: 3, 4, 5, or 6; relative density (alpha modification): 19.84; melting pt: 640°C; boiling pt: 3230°C
Word Origin
C20: named after the dwarf planet Pluto because Pluto lies beyond Neptune and plutonium was discovered soon after neptunium
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for plutonium 239

plutonium

n.

transuranic element, 1942, from Pluto, the planet, + element ending -ium. Discovered at University of California, Berkeley, in 1941, the element named on suggestion of Seaborg and Wahl because it follows neptunium in the periodic table as Pluto follows Neptune in the Solar System. The name plutonium earlier had been proposed for barium and was sometimes used in this sense early 19c.

Online Etymology Dictionary, © 2010 Douglas Harper
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plutonium 239 in Medicine

plutonium plu·to·ni·um (plōō-tō'nē-əm)
n.
Symbol Pu
A naturally radioactive, metallic transuranic element, occurring in uranium ores or produced artificially by neutron bombardment of uranium. Its longest-lived isotope is Pu 244 with a half-life of 77 million years. Atomic number 94; melting point 640°C; boiling point 3,228°C; specific gravity 19.84; valence 3, 4, 5, 6.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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plutonium 239 in Science
plutonium
  (pl-tō'nē-əm)   
Symbol Pu
A silvery, radioactive metallic element of the actinide series that has the highest atomic number of all naturally occurring elements. It is found in minute amounts in uranium ores and is produced artificially by bombarding uranium with neutrons. It is absorbed by bone marrow and is highly poisonous. Plutonium is used in nuclear weapons and as a fuel in nuclear reactors. Its longest-lived isotope is Pu 244 with a half-life of 76 million years. Atomic number 94; melting point 640°C; boiling point 3,232°C; specific gravity 19.84; valence 3, 4, 5, 6. See Periodic Table.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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plutonium 239 in Culture
plutonium [(plooh-toh-nee-uhm)]

A radioactive chemical element that is artificially derived from uranium.

Note: Plutonium is used in nuclear reactors.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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