ETYM Greek, a turning in; en in + trope a turn, from trepein to turn.
Is a measure of the unavailability of energy in a substance.
(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.
Amount of unavailable energy in a thermodynamic system; (process of running down to a) static condition.
In thermodynamics, a parameter representing the state of disorder of a system at the atomic, ionic, or molecular level; the greater the disorder, the higher the entropy. Thus the fast-moving disordered molecules of water vapor have higher entropy than those of more ordered liquid water, which in turn have more entropy than the molecules in solid crystalline ice.
In a closed system undergoing change, entropy is a measure of the amount of energy unavailable for useful work. At absolute zero (-273şC/-459.67şF/0K), when all molecular motion ceases and order is assumed to be complete, entropy is zero.