neptunium
/nɛpˈtuːniəm/
noun
- A silvery, radioactive metallic chemical element. It is created artificially from uranium and is used in research and in making plutonium.
- The lab safely stored a sample of neptunium in a special container.
- Neptunium is found in small amounts in spent nuclear fuel.
- Scientists study neptunium to understand how radioactive elements behave.