Tritium is a radioactive isotope of hydrogen with the symbol H-3. It is also known by several other synonyms such as hydrogen-3 and radioactive tritium. Additionally, it is sometimes referred to as T, trihydrogen, tritium gas, or tritiated water. Tritium is used in a variety of applications, including in nuclear weapons and as a tracer in biological and environmental studies. Although it is highly useful, tritium is also potentially dangerous due to its radioactivity. Synonyms for tritium provide a useful way to refer to this element depending on the context in which it is being discussed.