What is another word for heavy hydrogen?
Pronunciation: [hˈɛvi hˈa͡ɪdɹəd͡ʒən] (IPA) 
Heavy hydrogen is a commonly used term for the isotope of hydrogen, deuterium. Colloquially referred to as 'heavy water', deuterium is twice as heavy as the more commonly known isotope of hydrogen, referred to as protium. This heavy isotope of hydrogen can also be referred to as 'D-Hydrogen' or 'D'. Deuterium is a naturally occurring isotope of hydrogen, commonly found in seawater and used in the production of nuclear energy. In recent times, heavy hydrogen has also been referred to as 'isotope hydrogen' or 'D2' to distinguish it from the lighter, more abundant protium. Utilizing a diverse range of synonyms, this term is widely recognized throughout the scientific community.
