Lack of order, purpose, cause, or predictability in non-scientific parlance.
Strictly thermodynamic entropy. A measure of the amount of energy in a physical system that cannot be used to do work.
Entropy increases as matter and energy in the universe degrade to an ultimate state of inert uniformity
The thermodynamic free energy is the amount of work that a thermodynamic system can perform; it is the internal energy of a system minus the amount of energy that cannot be used to perform work. That unusable energy is given by the entropy of a system multiplied by the temperature of the system.  (Note that, for both Gibbs and Helmholtz free energies, temperature is assumed to be fixed, so entropy is effectively directly proportional to useless energy.).