Word Study
neptunium
CIDE DICTIONARY
neptunium, n. [NL.].
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. [PJC]
OXFORD DICTIONARY
neptunium, n. Chem. a radioactive transuranic metallic element produced when uranium atoms absorb bombarding neutrons.
Usage
Symb.: Np.
Etymology
NEPTUNE, as the next planet beyond Uranus, + -IUM
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