- the thermodynamic function of a system that is equal to its enthalpy minus the product of its absolute temperture and entropy: a decrease in the function is equal to the maximum amount of work available exclusive of that due to pressure times volume change during a reversible, isothermal, isobaric process.
- a thermodynamic property of a system equal to the difference between its enthalpy and the product of its temperature and its entropy. It is usually measured in joules
