What does deuterium mean?
Deuterium is a stable isotope of hydrogen, symbolized ²H or simply D, whose nucleus contains one proton and one neutron rather than the lone proton found in ordinary hydrogen. This extra particle makes it about twice as heavy as normal hydrogen, which is why water molecules built from deuterium are known as heavy water. Discovered in 1931 by the American chemist Harold Urey, who received the Nobel Prize for the work, deuterium occurs naturally but makes up only a tiny fraction of all hydrogen on Earth. It plays an important role in modern science: chemists substitute it into molecules to trace reaction pathways, astronomers use its abundance to probe conditions in the early universe, and physicists study it as a fuel for nuclear fusion. The word is technical, appearing mainly in scientific contexts, usually alongside terms like heavy water, deuteron, or deuterated.
nounA stable isotope of hydrogen whose nucleus contains one proton and one neutron, making it roughly twice as heavy as ordinary hydrogen; it is symbolized ²H or D and occurs naturally in small amounts in water.
- The stable hydrogen isotope ²H (symbol D) containing one proton and one neutron in its nucleus, about twice the mass of ordinary hydrogen.
"Heavy water, in which deuterium replaces ordinary hydrogen, was a critical material in the early development of nuclear reactors."
"The researchers enriched the sample by replacing protium with deuterium at key molecular positions."
"In stars more massive than the Sun, deuterium fusion marks one of the earliest stages of energy generation."
Rarely used; as a mass noun referring to a substance, deuterium typically takes no plural. A plural may appear only when counting distinct isotopic samples or types in specialized scientific prose.
"The spectra suggested the sample contained traces of several distinct deuteriums from different sources."
Discovered only in 1931, deuterium earned its discoverer Harold Urey a Nobel Prize — and its 'heavy water' form became so strategically vital that Allied commandos risked their lives to sabotage Nazi supplies of it.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of deuterium
The name deuterium derives from the Greek word "deuteros," meaning "second," because it was the second isotope of hydrogen to be identified. It was coined after Urey and his colleagues detected the isotope spectroscopically in 1931. Related coinages from the same root include "deuteron," the name for the deuterium nucleus itself.
Related word forms
How deuterium is actually used
A technical term used chiefly in physics, chemistry, nuclear science, and astronomy; in general writing it appears most often alongside "heavy water" (deuterium oxide). Its compounds are described as "deuterated," and atoms of deuterium are sometimes called "deuterons" when referring to the bare nucleus.
Easily confused with deuterium
Deuterium is the stable hydrogen isotope with one neutron, whereas tritium is the radioactive hydrogen isotope with two neutrons.
Deuterium's nucleus contains a proton plus a neutron, while protium, the most common hydrogen isotope, consists of a proton alone.