deuterium
noun
deu·te·ri·um
dü-ˈtir-ē-əm 
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
Many companies are also exploring aneutronic fusion concepts, which seek to reduce neutron production and simplify reactor materials and maintenance compared with traditional deuterium-tritium designs.
—
Kaif Shaikh,
Interesting Engineering,
28 June 2026
The comet contains far more heavy hydrogen—in the form of an isotope called deuterium, which has one neutron and one proton—than any local space rock, a quality that tends to point to colder environs.
—
Joseph Howlett,
Scientific American,
22 June 2026
The ratio is also an important one because abundances of deuterium and hydrogen throughout the universe are thought to have been set during the Big Bang itself.
—
Robert Lea,
Space.com,
23 Apr. 2026
The co-author of a paper published today in the journal Nature Astronomy, Manzano explained that 3I/ATLAS contains 30 times the deuterium seen in other comets, as well as 40 times the amount that exists in Earth’s oceans.
—
Andrew Paul,
Popular Science,
23 Apr. 2026
See All Example Sentences for deuterium
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Kaif Shaikh,
Interesting Engineering,
28 June 2026
The comet contains far more heavy hydrogen—in the form of an isotope called deuterium, which has one neutron and one proton—than any local space rock, a quality that tends to point to colder environs.
—
Joseph Howlett,
Scientific American,
22 June 2026
The ratio is also an important one because abundances of deuterium and hydrogen throughout the universe are thought to have been set during the Big Bang itself.
—
Robert Lea,
Space.com,
23 Apr. 2026
The co-author of a paper published today in the journal Nature Astronomy, Manzano explained that 3I/ATLAS contains 30 times the deuterium seen in other comets, as well as 40 times the amount that exists in Earth’s oceans.
—
Andrew Paul,
Popular Science,
23 Apr. 2026
See All Example Sentences for deuterium
Cite this Entry
“Deuterium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/deuterium. Accessed 6 Jul. 2026.
Copy CitationKids Definition
deuterium
noun
deu·te·ri·um
d(y)ü-ˈtir-ē-əm
: 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
: 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
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