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