Definition of "entropy"

A measure of the disorder present in a system.

1. (Boltzmann definition) A measure of the disorder directly proportional to the natural logarithm of the number of microstates yielding an equivalent thermodynamic macrostate.  examples

2. (information theory) Shannon entropy  examples

(thermodynamics, countable) A measure of the amount of energy in a physical system that cannot be used to do work.  examples

The capacity factor for thermal energy that is hidden with respect to temperature.  examples

The dispersal of energy; how much energy is spread out in a process, or how widely spread out it becomes, at a specific temperature.  examples

(statistics, information theory, countable) A measure of the amount of information and noise present in a signal.  examples

(uncountable) The tendency of a system that is left to itself to descend into chaos.  examples