1. 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 Noun
2. A unit of inductance in which an induced electromotive force of one volt is produced when the current is varied at the rate of one ampere per second Noun
3. The constant of proportionality relating the energy of a photon to its frequency; approximately 6.626 x 10^-34 joule-second Noun
4. The 8th letter of the Roman alphabet Noun
5. (thermodynamics) a thermodynamic quantity equal to the internal energy of a system plus the product of its volume and pressure Noun