inversion point

in phase transitions
https://doi.org/10.1351/goldbook.I03149
The temperature (pressure) at which one polymorph of a solid phase changes into another at constant pressure (temperature).
See:
polymorphic transition
Source:
PAC, 1994, 66, 577. (Definitions of terms relating to phase transitions of the solid state (IUPAC Recommendations 1994)) on page 584 [Terms] [Paper]