plutonium

noun
plu·​to·​ni·​um | \ plü-ˈtō-nē-əm How to pronounce plutonium (audio) \

Definition of plutonium

: 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 Chemical Elements Table

Examples of plutonium in a Sentence

Recent Examples on the Web Los Alamos is preparing to resume and ramp up production of the plutonium cores used to trigger nuclear weapons. Washington Post, "Family members of victims request delay in inmate’s execution, citing virus fears," 7 July 2020 Nervousness about countries using civil programmes to acquire the plutonium needed for bombmaking was soon put to rest. The Economist, "If nuclear power had taken off What if nuclear power had taken off in the 1970s?," 4 July 2020 The waste site, known alternatively as the Tomb, holds more than 3.1 million cubic feet — or 35 Olympic-size swimming pools — of U.S.-produced radioactive soil and debris, including lethal amounts of plutonium. Susanne Rust, Los Angeles Times, "U.S. says leaking nuclear waste dome is safe; Marshall Islands leaders don’t believe it," 1 July 2020 The first came in 1942, when Enrico Fermi was having trouble keeping his plutonium chain reaction running at a government research complex. Time, "1945: Chien-Shiung Wu," 5 Mar. 2020 Hanford made plutonium for nuclear weapons during the Cold War. oregonlive, "Hanford nuclear site’s inspection shortcomings revealed in watchdog report; parts of vast facility not entered in 50 years," 25 Feb. 2020 In contrast, the implosion bomb started with a ball of plutonium surrounded by a large sphere of conventional explosives. New York Times, "Fourth Spy at Los Alamos Knew A-Bomb’s Inner Secrets," 27 Jan. 2020 Bomb radiocarbon did not pose a significant threat to human health—certainly not compared with other elements released by bombs, such as plutonium and uranium. Carl Zimmer, The Atlantic, "Nuclear Tests Marked Life on Earth With a Radioactive Spike," 20 Mar. 2020 The Trump administration has also shown support for another alternative, known as reprocessing, that involves separating plutonium and uranium from spent fuel to make new fuel that can be used again. Josh Siegel, Washington Examiner, "Daily on Energy: Trump administration gives a little in acknowledging climate change," 24 Feb. 2020

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.

See More

First Known Use of plutonium

1942, in the meaning defined above

History and Etymology for plutonium

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

Keep scrolling for more

Learn More about plutonium

Time Traveler for plutonium

Time Traveler

The first known use of plutonium was in 1942

See more words from the same year

Statistics for plutonium

Last Updated

11 Jul 2020

Cite this Entry

“Plutonium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/plutonium. Accessed 11 Jul. 2020.

Keep scrolling for more

More Definitions for plutonium

plutonium

noun
How to pronounce plutonium (audio)

English Language Learners Definition of plutonium

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

plutonium

noun
plu·​to·​ni·​um | \ plü-ˈtō-nē-əm How to pronounce plutonium (audio) \

Kids Definition of plutonium

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

plutonium

noun
plu·​to·​ni·​um | \ plü-ˈtō-nē-əm How to pronounce plutonium (audio) \

Medical Definition of plutonium

: 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 Chemical Elements Table

Keep scrolling for more

More from Merriam-Webster on plutonium

Rhyming Dictionary: Words that rhyme with plutonium

Spanish Central: Translation of plutonium

Nglish: Translation of plutonium for Spanish Speakers

Britannica.com: Encyclopedia article about plutonium

Comments on plutonium

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

WORD OF THE DAY

See Definitions and Examples »

Get Word of the Day daily email!

Test Your Vocabulary

Words for Summer: A Quiz

  • a closeup of a sunflower
  • Which of the following words means “of or relating to summer”?
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!