Synonyms: atomic number 1, hydrogen, H
Definition: 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
Similar words: element, chemical element
Definition: any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter
Similar words: gas
Definition: a fluid in the gaseous state having neither independent shape nor volume and being able to expand indefinitely