A nonmetallic univalent element that is normally a colorless and odorless highly flammable diatomic gas; the simplest and lightest and most abundant element in the universe WordNet 3.0 & Open English WordNet

Hydrogen is a chemical element; it has symbol H and atomic number 1. Wikipedia

Hydrium is a former name for hydrogen. Wikipedia Disambiguation

Chemical element with symbol H and atomic number 1. Wikipedia Disambiguation

Chemical element with symbol H and atomic number 1; lightest and most abundant substance in the universe Wikidata

A flammable colourless gas that is the lightest and most abundant element in the universe. It occurs mainly in water and in most organic compounds and is used in the production of ammonia and other chemicals, in the hydrogenation of fats and oils, and in welding. OmegaWiki

The lightest chemical element (symbol H), with an atomic number of 1 and atomic weight of 1.00794. Wiktionary

Chemical element. Wiktionary (translation)