standard electromotive force
Quantity defined by E° =- Δ r G° n F = R T n F ln, where Δ r G° is the standard Gibbs energy of the cell reaction in the direction in which reduction occurs at the right-hand electrode in the diagram representing the cell ('reduction at right'), K° is the standard equilibrium constant for this reaction, n its charge number, F the Faraday constant, R the gas constant and T the thermodynamic temperature.
Green Book, 2nd ed., p. 58 (