https://doi.org/10.1351/goldbook.M03871
A term that describes the state of a phase in which an energy barrier considerably higher than \(k\ T\) must be surmounted before this phase can transform to a phase of lower molar Gibbs energy and molar Helmholtz energy, where \(k\) is the Boltzmann constant and \(T\) the thermodynamic temperature.
Note: In a thermodynamic sense, the equilibrium state is the state with the lowest molar Gibbs energy; a metastable state corresponds to a relative minimum in the molar Gibbs energy.