deuterium

American  

[doo-teer-ee-uhm, dyoo-] / duˈtɪər i əm, dju- /

noun

Chemistry.

1. an isotope of hydrogen, having twice the mass of ordinary hydrogen; heavy hydrogen. 2 H, D; 2.01; 1.

---

deuterium British  

/ djuːˈtɪərɪəm /

noun

1. a stable isotope of hydrogen, occurring in natural hydrogen (156 parts per million) and in heavy water: used as a tracer in chemistry and biology. Symbol: D or ²H; atomic no: 1; atomic wt: 2.014; boiling pt: –249.7°C

---

deuterium Scientific  

/ do̅o̅-tîr′ē-əm /

1. An isotope of hydrogen whose nucleus has one proton and one neutron and whose atomic mass is 2. Deuterium is used widely as a tracer for analyzing chemical reactions, and it combines with oxygen to form heavy water.

2. Also called heavy hydrogen

3. See Note at heavy water

---

Etymology

Origin of deuterium

1933; < Greek deúter ( os ) second ( see deutero-) + -ium

Compare meaning

How does deuterium compare to similar and commonly confused words? Explore the most common comparisons:

• deuterium vs. hydrogen

Example Sentences

See Examples For:

deuterium

The findings come from an analysis of the comet's unusual water composition, which revealed extraordinarily high levels of deuterium, a heavier form of hydrogen.

From Science Daily ● May 8, 2026

First-generation reactors will almost certainly be fueled by the hydrogen isotopes deuterium and tritium.

From The Wall Street Journal ● Dec. 28, 2025

A good thing to note is that deuterium, a stable isotope of hydrogen, is much less expensive and can be found in seawater.

From Los Angeles Times ● Sep. 15, 2024

Researchers, working on nuclear fusion, are fusing tritium and deuterium together to maximize the amount of energy created in one small area.

From Los Angeles Times ● Sep. 15, 2024

His discovery was a triumph of scientific deduction, for the neutron, which gives deuterium its additional weight, was not discovered until many months after he identified the isotope itself.

From "Big Science" by Michael Hiltzik