uranium 235

noun

: a light isotope of uranium of mass number 235 that constitutes less than one percent of natural uranium, that when bombarded with slow neutrons undergoes rapid fission into smaller atoms with the release of neutrons and energy, and that is used in nuclear reactors and atomic bombs

Examples of uranium 235 in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Space reactor challenge Fuel rods made with uranium 235 oxide distributed in a metal or ceramic matrix comprise the core of a standard fission reactor. — Jacek Krywko, Ars Technica, 22 July 2024 Fission happens when a slow-moving neutron is absorbed by a uranium 235 nucleus and splits it into two lighter nuclei, releasing huge amounts of energy and excess, very fast neutrons. — Jacek Krywko, Ars Technica, 22 July 2024

Word History

First Known Use

1940, in the meaning defined above

Time Traveler
The first known use of uranium 235 was in 1940

Browse Nearby Words

uranium
uranium 235
uranium 238
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Cite this Entry

“Uranium 235.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/uranium%20235. Accessed 1 Apr. 2025.

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Kids Definition

uranium 235

noun
: a light form of uranium of mass number 235 that when bombarded with neutrons splits rapidly into smaller atoms with the release of neutrons and atomic energy

Medical Definition

uranium 235

noun
: a light isotope of uranium of mass number 235 that when bombarded with slow neutrons undergoes rapid fission into smaller atoms with the release of neutrons and energy
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