# Gibbs free energy

## English

### Etymology

For Josiah Willard Gibbs, American physicist.

### Noun

1. (physics, chemistry, thermodynamics) The difference between the enthalpy of a system and the product of its entropy and absolute temperature: a measure of the useful work obtainable from a thermodynamic system at constant temperature and pressure.
${\displaystyle \Delta G=\Delta H-T\Delta S}$ and ${\displaystyle G=H-TS}$ where G is Gibbs free energy, H is enthalpy, T is temperature, and S is entropy.