h meaning and definition

H noun

Definition of H (noun)

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
   • synonyms: atomic number 1, hydrogen
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
   • synonyms: henry
3. the constant of proportionality relating the energy of a photon to its frequency; approximately 6.626 x 10^-34 joule-second
   • synonyms: Planck's constant
4. the 8th letter of the Roman alphabet
5. the 8th letter of the Roman alphabet
6. (thermodynamics) a thermodynamic quantity equal to the internal energy of a system plus the product of its volume and pressure
   • "enthalpy is the amount of energy in a system capable of doing mechanical work"
   • synonyms: enthalpy, heat content, total heat