plutonium

play
noun plu·to·ni·um \plü-ˈtō-nē-əm\

Definition of plutonium

  1. :  a radioactive metallic element similar chemically to uranium that is formed as the isotope 239 by decay of neptunium and found in minute quantities in pitchblende, that undergoes slow disintegration with the emission of an alpha particle to form uranium 235, and that is fissionable with slow neutrons to yield atomic energy — see element table

Recent Examples of plutonium from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'plutonium'. Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of plutonium

New Latin, from Pluton-, Pluto, the planet Pluto


PLUTONIUM Defined for English Language Learners

plutonium

play
noun

Definition of plutonium for English Language Learners

  • : a radioactive element that is used to make nuclear energy and nuclear weapons


PLUTONIUM Defined for Kids

plutonium

play
noun plu·to·ni·um \plü-ˈtō-nē-əm\

Definition of plutonium for Students

  1. :  a radioactive metallic chemical element formed from neptunium and used for releasing atomic energy


Medical Dictionary

plutonium

play
noun plu·to·ni·um \plü-ˈtō-nē-əm\

Medical Definition of plutonium

  1. :  a radioactive metallic element similar chemically to uranium that is formed as the isotope 239 by decay of neptunium and found in minute quantities in pitchblende, that undergoes slow disintegration with the emission of an alpha particle to form uranium 235, and that is fissionable with slow neutrons to yield atomic energy—symbol Pu; see element table



Seen and Heard

What made you want to look up plutonium? Please tell us where you read or heard it (including the quote, if possible).

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

WORD OF THE DAY

to bring about or cause (something)

Get Word of the Day daily email!

Test Your Vocabulary

The Emoji Quiz

  • emoji-the-quiz
  • What phase of the moon is this: 🌖 ?
Spell It

Can you spell these 10 commonly misspelled words?

TAKE THE QUIZ
Add Diction

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!