Miscibility
The ability of two liquids to mix in all proportions to form a single homogeneous phase.
Unit
Dimensionless
In depth
Miscibility requires that the attractions between unlike molecules be comparable to those within each pure liquid, which in practice means similar polarity and hydrogen-bonding ability. Some pairs are only partially miscible, dissolving in each other up to a limit that usually widens with temperature.
Examples in the real world
Ethanol and water mix completely; phenol and water are partially miscible below 66 °C.