deuterium

noun

deu·​te·​ri·​um dü-ˈtir-ē-əm How to pronounce deuterium (audio)
 also  dyü-
: an isotope of hydrogen that has one proton and one neutron in its nucleus and that has twice the mass of ordinary hydrogen
symbol D

called also heavy hydrogen

Examples of deuterium 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.
Building a fusion reactor Fusion occurs when two types of hydrogen atoms, deuterium and tritium, collide in extreme conditions. Farhat Beg, The Conversation, 8 Jan. 2025 When lasers hit the outside of this capsule, their energy is converted into X-rays that then blast the fuel pellet, which consists of a diamond outer shell coated on the inside with deuterium and tritium fuel. IEEE Spectrum, 6 Feb. 2024 On Earth, scientists are aiming to fuse deuterium and tritium—both isotopes, or versions, of hydrogen. Margherita Bassi, Smithsonian Magazine, 18 Apr. 2025 Fuel for fusion is abundant, derived from deuterium, found in seawater, and tritium extracted from lithium. Ella Nilsen, CNN Money, 6 May 2025 See All Example Sentences for deuterium

Word History

Etymology

New Latin, from Greek deuteros second

First Known Use

1933, in the meaning defined above

Time Traveler
The first known use of deuterium was in 1933

Browse Nearby Words

Cite this Entry

“Deuterium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/deuterium. Accessed 8 Jul. 2025.

Kids Definition

deuterium

noun
deu·​te·​ri·​um d(y)ü-ˈtir-ē-əm How to pronounce deuterium (audio)
: the hydrogen isotope that is twice the mass of ordinary hydrogen

called also heavy hydrogen

Medical Definition

deuterium

noun
deu·​te·​ri·​um d(y)ü-ˈtir-ē-əm How to pronounce deuterium (audio)
: an isotope of hydrogen that has one proton and one neutron in its nucleus and that has twice the mass of ordinary hydrogen

called also heavy hydrogen

More from Merriam-Webster on deuterium

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