Regular solution

In chemistry, a regular solution is a solution whose entropy of mixing is equal to that of an ideal solution with the same composition, but is non-ideal due to a nonzero enthalpy of mixing. Such a solution is formed by random mixing of components of similar molar volume and without strong specific interactions, and its behavior diverges from that of an ideal solution by showing phase separation at intermediate compositions and temperatures. Its entropy of mixing is equal to that of an ideal solution with the same composition, due to random mixing without strong specific interactions. For two components

This keyword could refer to multiple things. Here are some suggestions: