standard equilibrium constant, \(K^{\unicode{x26ac}}\), K

Synonym: thermodynamic equilibrium constant
https://doi.org/10.1351/goldbook.S05915
Quantity defined by K° = e- Δ r G° / R T where Δ r G° is the standard reaction Gibbs energy, R the gas constant and T the thermodynamic temperature. Some chemists prefer the name thermodynamic equilibrium constant and the symbol K.
Source:
Green Book, 2nd ed., p. 50 (https://dev.goldbook.iupac.org/files/pdf/green_book_2ed.pdf)