tri·​ti·​um | \ ˈtri-tē-əm How to pronounce tritium (audio) , ˈtri-shē- \

Definition of tritium

: a radioactive isotope of hydrogen that has one proton and two neutrons in its nucleus and that has three times the mass of ordinary hydrogen symbol T

Examples of tritium in a Sentence

Recent Examples on the Web Priest said that Potvin’s claim about the amount of tritium, a radioactive isotope, in the water was exaggerated by 10,000 times. Mike Damiano,, 26 July 2022 Deuterium has one proton and one neutron while tritium has one proton and two neutrons. David Donovan, The Conversation, 4 Apr. 2022 Better methods must also be developed for on-site production and handling of tritium to use as fuel. Philip Ball, Scientific American, 2 Feb. 2022 The 50 million watts is only the power supplied directly to the deuterium and tritium fuel. Don Lincoln, CNN, 11 Feb. 2022 Set up to reflect the design of ITER, and with the mix of deuterium and tritium fuel that will be used there, JET made the largest sustained fusion reaction yet. John Timmer, Ars Technica, 9 Feb. 2022 That lets the pilot project avoid having to source rare, radioactive tritium and deal with the excess heat and generated radioactivity. Daniel Clery, Science | AAAS, 16 June 2021 The process can produce tritium, which is commonly used in commercial applications such as wristwatches and exit signs. James Conca, Forbes, 9 Nov. 2021 The sporty 1980’s model features a stark black reverse-panda dial for contrast, tritium luminous plats, and a bulky rotating time bezel set within a 40 mm case. Demetrius Simms, Robb Report, 9 Nov. 2021 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'tritium.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of tritium

1933, in the meaning defined above

History and Etymology for tritium

New Latin, from Greek tritos third — more at third entry 1

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The first known use of tritium was in 1933

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Last Updated

3 Aug 2022

Cite this Entry

“Tritium.” Dictionary, Merriam-Webster, Accessed 15 Aug. 2022.

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More Definitions for tritium


tri·​ti·​um | \ ˈtrit-ē-əm How to pronounce tritium (audio) , ˈtrish-ē- How to pronounce tritium (audio) \

Medical Definition of tritium

: a radioactive isotope of hydrogen that has three times the mass of ordinary hydrogen symbol T

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