OT:
As i have remembered, Entropy was described by our instructor as the measure of the random movements of molecules. The movements of molecules are uncertain, so entropy is also described as the measure of uncertainty. My previous instructors also defined entropy the same as disorder.... Since it is in disorder, you cannot contain it or harness entropy, therefore it is considered as a loss of energy. A change in entropy means that there is a loss of energy.
That's the reason in an isentropic process, it is considered as an ideal state bcoz losses of energy is not considered since constant entropy is assumed...