heavy hydrogen heavy hitter • heavy-jawed · · · Info · Definitions · Synonyms · Characters · · heavy hydrogen · · Text Common · · Latin · · Scripts 14 · · Length 5 · · Syllables Definitions · · · (noun) an isotope of hydrogen which has one neutron (as opposed to zero neutrons in hydrogen). Synonyms: deuterium, heavy hydrogen. · · Noun Definition 1 Synonyms · · · deuterium · · Synonym 1 Characters · · space U+0020 a latin small letter a U+0061 d latin small letter d U+0064 e latin small letter e U+0065 g latin small letter g U+0067 h latin small letter h U+0068 n latin small letter n U+006E o latin small letter o U+006F r latin small letter r U+0072 v latin small letter v U+0076 y latin small letter y U+0079