PLUTONIUM
- the chemical element with atomic number 94 [n PLUTONIUMS]
- a naturally radioactive, silvery, metallic transuranic element [n -S]
- 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