hydrogen
Cross references: 1. deuterium 2. tritium 3. element hy.dro.gen \'hi--dr*-j*n\ \hi--'dra:j-*-n*s\ n [F hydroge'ne, fr. hydr- + -ge'ne -gen; fr. the fact that w]ater is generated by its combustion : a nonmetallic univalent element that is the simplest and lightest of the elements, is normally a colorless odorless highly flammable diatomic gas, and is used esp. in the production of its economic compounds - hy.drog.e.nous aj