a measure of the energy content of a system per unit mass
See enthalpy in American Heritage Dictionary 4
(ĕnˈthălˌpē, ĕn-thălˈ-)
noun Symbol Hpl.en·thal·pies
A thermodynamic function of a system, equivalent to the sum of the internal energy of the system plus the product of its volume multiplied by the pressure exerted on it by its surroundings.