Definition of deuterium in English:


(also D)

Pronunciation /ˌdyo͞oˈtirēəm/ /ˌdjuˈtɪriəm/


  • A stable isotope of hydrogen with a mass approximately twice that of the usual isotope.

    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

    ‘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.’
    • ‘The basic principles are relatively simple to lay out: a high energy laser is used to heat and compress a small amount of deuterium, a stable isotope of hydrogen.’
    • ‘If necessary, stocks of deuterium, tritium, hydrogen, and helium were supplied from on-board stores.’


1930s modern Latin, from Greek deuteros ‘second’.