1. A nonmetallic univalent element that is normally a colourless and odourless highly flammable diatomic gas; the simplest and lightest and most abundant element in the universe
   "Hydrogen fuel cells are being developed as a clean energy source";
   - H, atomic number 1

Derived forms: hydrogens

Type of: chemical element, element, gas

Part of: H2O, water

Encyclopedia: Hydrogen, 1H