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Syllabification: plu·to·ni·um
Pronunciation: /plo͞oˈtōnēəm

Definition of plutonium in English:


The chemical element of atomic number 94, a dense silvery radioactive metal of the actinide series, used as a fuel in nuclear reactors and as an explosive in nuclear fission weapons. Plutonium only occurs in trace amounts in nature but is manufactured in nuclear reactors from uranium-238. (Symbol: Pu)
Example sentences
  • The only manufacturing left on the site when reprocessing goes will be the plant for making nuclear fuel from plutonium and uranium oxides.
  • Workers at the facility were exposed to radiation as well as the chemicals uranium, plutonium and fluorine.
  • To develop a comprehensive set of nuclear weapons, enriched plutonium and uranium are needed.


late 18th century: from Greek Ploutōn 'Pluto', on the pattern of neptunium, being the next planet beyond Neptune.

Definition of plutonium in:

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