noun ·Uncommon ·Advanced level

Definitions

Noun

1. 1
   The transuranic chemical element with atomic number 94 and symbol Pu: a silvery-gray fissile radioactive actinide metal that tarnishes when exposed to air. uncountable, usually

   "Plutonium? You mean this sucker's nuclear?"

2. 2
   a solid silvery grey radioactive transuranic element whose atoms can be split when bombarded with neutrons; found in minute quantities in uranium ores but is usually synthesized in nuclear reactors; 13 isotopes are known with the most important being plutonium 239 wordnet
3. 3
   Alternative form of ploutonion. alt-of, alternative, countable, historical, usually

Synonyms

All synonyms

atomic number 94elementpuradioelementradiumsilver

Example

More examples

"Plutonium-244 has a half-life of 80 million years."

Etymology

After Pluto (dwarf planet) + -n- + -ium. More in Wikipedia at plutonium § History.

Related phrases

plutonium bombplutonium dioxideplutonium enrichmentplutonium hydrideplutonium pitplutonium-239reactor-grade plutoniumweapon-grade plutonium

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.