equilibration

https://doi.org/10.1351/goldbook.E02175
The operation by which a system of two or more phases is brought to a condition where further changes with time do not occur. This term is not synonymous with pre-equilibrium and should not be used in that sense.
Source:
PAC, 1993, 65, 2373. (Nomenclature for liquid-liquid distribution (solvent extraction) (IUPAC Recommendations 1993)) on page 2377 [Terms] [Paper]