Adiabatic equilibrium

From Glossary of Meteorology

adiabatic equilibrium

A vertical distribution of temperature and pressure in an atmosphere in hydrostatic equilibrium such that an air parcel displaced adiabatically will continue to possess the same temperature and pressure as its surroundings, so that no restoring force acts on a parcel displaced vertically.

A layer in adiabatic equilibrium has uniform equivalent potential temperature. The state of adiabatic equilibrium is approached in a layer of air in which there is strong vertical mixing.
Compare static stability.