hydrogen (n.)youdaoicibaDictYouDict[hydrogen 词源字典]
1791, from French hydrogène, coined 1787 by G. de Morveau, Lavoisier, Berthollet, and Fourcroy from Greek hydr-, stem of hydor "water" (see water (n.1)) + French -gène "producing" (see -gen). So called because it forms water when exposed to oxygen. Nativized in Russian as vodorod; in German, it is wasserstoff, "water-stuff." An earlier name for it in English was Cavendish's inflammable air (1767). Hydrogen bomb first recorded 1947; shortened form H-bomb is from 1950.[hydrogen etymology, hydrogen origin, 英语词源]
thermonuclear (adj.)youdaoicibaDictYouDict
1938 with reference to stars, 1953 of weapons (technically only to describe the hydrogen bomb), from thermo- + nuclear.
H-bombyoudaoicibaDictYouDict
"Another term for hydrogen bomb", 1950s: from H2 (denoting hydrogen) + bomb.