a stable isotope of hydrogen, occurring in natural hydrogen (156 parts per million) and in heavy water: used as a tracer in chemistry and biology. Symbol: D or 2H; atomic no: 1; atomic wt: 2.014; boiling pt: –249.7°C
Word origin
C20: New Latin; see deutero-, -ium; from the fact that it is the second heaviest hydrogen isotope
deuterium in American English
(duˈtɪriəm; djuˈtɪriəm)
US
noun
a hydrogen isotope used in nuclear reactors, accelerators, etc.: symbol, D; at. wt., 2.0141