D defs.my
Entry 1 sense Webster, 1913

Neptunium

/nĕptū'nēəm/ · Nep·tu·ni·um · IPA /nɛpˈtjuːniəm/
01 n. A radioactive metallic element of atomic number 93, produced in nuclear reactors from Plutonium or Uranium. Symbol Np; The atomic weight …
  1. 1.
    A radioactive metallic element of atomic number 93, produced in nuclear reactors from Plutonium or Uranium. Symbol Np; The atomic weight of the most stable isotope is 237.0482.