biphasic system

in liquid–liquid extraction
https://doi.org/10.1351/goldbook.10205
Equilibrium system containing two or more solvents forming two phases with a single interface.
Source:
PAC, 2016, 88, 517. 'Glossary of terms used in extraction (IUPAC Recommendations 2016)' on page 532 (https://doi.org/10.1515/pac-2015-0903)