1: (thermodynamics) a measure of the amount of energy in a system that is available for doing work; entropy increases as matter and energy in the universe degrade to an ultimate state of inert uniformity [ant: ectropy] 2: (communication theory) a numerical measure of the uncertainty of an outcome; "the signal contained thousands of bits of information" [syn: information, selective information] Source: WordNet ? 1.6, ? 1997 Princeton University