mesophase

https://doi.org/10.1351/goldbook.M03849
A phase occurring over a definite range of temperature, pressure, or concentration within the mesomorphic state.
Source:
PAC, 2002, 74, 493. 'Definitions of basic terms relating to polymer liquid crystals (IUPAC Recommendations 2001)' on page 495 (https://doi.org/10.1351/pac200274030493)
This definition replaces an earlier definition of mesophase.