Definition of deuterium in English:

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Pronunciation: /djuːˈtɪərɪəm/


[mass noun] Chemistry
A stable isotope of hydrogen with a mass approximately twice that of the usual isotope. (Symbol: D)
Example sentences
  • The most easily attained fusion reaction involves fusing nuclei of the two isotopes of hydrogen, deuterium and tritium, to make nuclei of helium.
  • Although many nuclei can be fused, this subject normally refers to fusion of hydrogen isotopes deuterium or tritium to form helium.
  • We know that for a fact because we've measured the isotope ratio of deuterium and hydrogen.

Deuterium atoms have a neutron as well as a proton in the nucleus, and the isotope is present to about 1 part in 6,000 in naturally occurring hydrogen. It is used as a fuel in thermonuclear bombs, and heavy water (D2O) is used as a moderator in nuclear reactors.


1930s: modern Latin, from Greek deuteros 'second'.

For editors and proofreaders

Line breaks: deu¦ter|ium

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