An adiabatic process is one in which no heat is exchanged with the surroundings (\( Q = 0 \)).
If this adiabatic process is also reversible, then the entropy of the system remains constant throughout the process.
A process in which entropy remains constant is called an isoentropic process.
So, all reversible adiabatic processes are isoentropic.
Thus, in thermodynamics, adiabatic and reversible processes are referred to as isoentropic processes.