Noun: neptunium nep't(y)oo-nee-um
- A radioactive transuranic metallic element; found in trace amounts in uranium ores; a by-product of the production of plutonium
"Neptunium was the first synthetic transuranic element to be discovered";
- Np, atomic number 93
Derived forms: neptuniums
Type of: metal, metallic element
Encyclopedia: Neptunium