What does "neptunium" mean?

The transuranic chemical element with atomic number 93 and symbol Np.

How do you pronounce "neptunium"?

Pronounced //nɛpˈtjuːniəm//.

Common synonyms include: np, actinide metal, atomic number 93, element, neptunium element, neptunium isotopes.

/nɛpˈtjuːniəm/ noun

noun ·Rare ·Advanced level

Noun

1
The transuranic chemical element with atomic number 93 and symbol Np. uncountable
2
a radioactive transuranic metallic element; found in trace amounts in uranium ores; a by-product of the production of plutonium wordnet

From Neptune + -ium, after the planet. The previous element is uranium, named after the previous planet: Uranus.