A lot vs. Alot: 9 Grammatical Pitfalls
1933, coined by U.S. chemist Harold C. Urey, with Modern Latin ending + Greek deuterion, neuter of deuterios "having second place," from deuteros "second," from duo (see two). So called because it is twice the mass of hydrogen.
deuterium deu·te·ri·um (dōō-tēr'ē-əm, dyōō-)
An isotope of hydrogen with one proton and one neutron in the nucleus having an atomic weight of 2.014. Also called heavy hydrogen, hydrogen-2.
An isotope of hydrogen whose nucleus has one proton and one neutron and whose atomic mass is 2. Deuterium is used widely as a tracer for analyzing chemical reactions, and it combines with oxygen to form heavy water. Also called heavy hydrogen. See Note at heavy water.
isotope of hydrogen with atomic weight of approximately 2. Its nucleus, consisting of one proton and one neutron, has double the mass of the nucleus of ordinary hydrogen. Deuterium is a stable atomic species found in natural hydrogen compounds to the extent of 0.014 to 0.015 percent.