Definition of tritium in English:

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Pronunciation: /ˈtridēəm/


A radioactive isotope of hydrogen with a mass approximately three times that of the common protium isotope. (Symbol: T)

Discovered in 1934, tritium has two neutrons as well as a proton in the nucleus. It occurs in minute traces in nature and can be made artificially from lithium or deuterium in nuclear reactors; it is used as a fuel in thermonuclear bombs.

Example sentences
  • Although many nuclei can be fused, this subject normally refers to fusion of hydrogen isotopes deuterium or tritium to form helium.
  • Although tritium can be a gas, its most common form is in water, because, like non-radioactive hydrogen, radioactive tritium reacts with oxygen to form water.
  • These products contain tiny glass vials filled with a radioactive gas such as tritium.


1930s: from modern Latin, from Greek tritos 'third'.

For editors and proofreaders

Syllabification: trit·i·um

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