noun (n)

• 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.substance)

  Synonym:
  atomic number 1, hydrogen
  

  source: wordnet30
• 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.quantity)

  Synonym:
  henry
  

  source: wordnet30
• the constant of proportionality relating the energy of a photon to its frequency; approximately 6.626 x 10^-34 joule-second(noun.quantity)

  source: wordnet30
• the 8th letter of the Roman alphabet(noun.communication)

  source: wordnet30
• (thermodynamics) a thermodynamic quantity equal to the internal energy of a system plus the product of its volume and pressure(noun.attribute)

  Example:
  EntHalpy is tHe amount of energy in a system capable of doing mecHanical work.
  

  Synonym:
  enthalpy, heat content, total heat
  

  source: wordnet30