plutonium

plu·to·ni·um

noun \plü-ˈtō-nē-əm\

Definition of PLUTONIUM

: a radioactive metallic element similar chemically to uranium that is formed as the isotope 239 by decay of neptunium and found in minute quantities in pitchblende, that undergoes slow disintegration with the emission of an alpha particle to form uranium 235, and that is fissionable with slow neutrons to yield atomic energy — see element table

Origin of PLUTONIUM

New Latin, from Pluton-, Pluto, the planet Pluto

First Known Use: 1942

Rhymes with PLUTONIUM

euphonium, harmonium, zirconium

plu·to·ni·um

noun \plü-ˈtō-nē-əm\   (Medical Dictionary)

Medical Definition of PLUTONIUM

: a radioactive metallic element similar chemically to uranium that is formed as the isotope 239 by decay of neptunium and found in minute quantities in pitchblende, that undergoes slow disintegration with the emission of an alpha particle to form uranium 235, and that is fissionable with slow neutrons to yield atomic energy—symbol Pu; see element table

plutonium

noun    (Concise Encyclopedia)

Radioactive (see radioactivity) metallic chemical element, chemical symbol Pu, atomic number 94. A member of the actinide series of transition elements, it is the most important transuranium element because of its use in certain types of nuclear reactors (see nuclear power) and in nuclear weapons. It is found in nature only in traces produced by natural neutron irradiation in uranium ores. It is produced artificially by neutron irradiation of uranium-238. Plutonium is a silvery metal that tarnishes in air; it is warm because of energy released in alpha decay. Its isotopes, all radioactive, are highly toxic radiological poisons (see radiation injury) because they give off alpha particles and are specifically absorbed by bone marrow.