tritium

noun

tri·​ti·​um ˈtri-tē-əm  ˈtri-shē- 

: 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

But Berzin said that the design will incorporate a layer of lithium that will form tritium when bombarded by neutrons from the stellarator. —ArsTechnica, 1 Apr. 2025

So, engineers will need to develop the ability to produce tritium within the fusion device itself. —Farhat Beg, The Conversation, 8 Jan. 2025

Some of the tool's other features include a lanyard hole on the top, along with four slots for optional vials of glow-in-the-dark (and slightly radioactive) tritium. —Ben Coxworth may 20, New Atlas, 20 May 2025

Due to its long lifespan in the Rolex catalog, several variations were made: While earlier examples feature tritium lume, later examples featured LumiNova and then Super-LumiNova. —Oren Hartov, Robb Report, 28 Mar. 2025

Word History

Etymology

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

First Known Use

1933, in the meaning defined above

Kids Definition

tritium

noun

tri·​ti·​um ˈtrit-ē-əm  ˈtrish-ē- 

: a rare radioactive form of hydrogen having atoms with three times the mass of ordinary light hydrogen atoms

Medical Definition

tritium

noun

tri·​ti·​um ˈtrit-ē-əm  ˈtrish-ē- 

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

—symbol T