Entropy

1. In physics: the ultimate state of maximum disorder to which the degradation of the matter and energy of the universe tends. A state of inert uniformity of component elements involving an absence of form, pattern, hierarchy or differentiation.

2. In cybernetics: the tendency of any closed system to move from a less to a more probable (unstable) state.

3. In communication theory: a measure of the efficiency of a system (as a code or a language) in transmitting information, being equal to the logarithm of the number of different messages that can be sent by selection from the same set of symbols and thus indicating the degree of initial uncertainty that can be resolved by any one message.