nep·tu·ni·um
noun/nepˈtjuːniəm/
/nepˈtuːniəm/
[uncountable] (symbol Np)
- a chemical element. Neptunium is a radioactive metal.
镎（放射性化学元素） Word Originlate 19th cent.: from Neptune, on the pattern of uranium (Neptune being the next planet beyond Uranus).