entropy

UK: /ˈɛntrəpi/ US: (en′trə pē)

WordReference Random House Unabridged Dictionary of American English © 2026

en•tro•py  (en′trə pē), n. 

1. Thermodynamics
   • (on a macroscopic scale) a function of thermodynamic variables, as temperature, pressure, or composition, that is a measure of the energy that is not available for work during a thermodynamic process. A closed system evolves toward a state of maximum entropy.
   • (in statistical mechanics) a measure of the randomness of the microscopic constituents of a thermodynamic system. Symbol: S
2. Thermodynamics, Computing (in data transmission and information theory) a measure of the loss of information in a transmitted signal or message.
3. Thermodynamics (in cosmology) a hypothetical tendency for the universe to attain a state of maximum homogeneity in which all matter is at a uniform temperature (heat death.)
4. Thermodynamics, Philosophy, Sociology a doctrine of inevitable social decline and degeneration.

• German Entropie (1865); see en-², -tropy

en•tro•pic  (en trō′pik, -trop′ik), adj.  en•tro′pi•cal•ly, adv. 

Collins Concise English Dictionary © HarperCollins Publishers::

entropy / ˈɛntrəpɪ/ noun ( -pies)

1. a thermodynamic quantity that changes in a reversible process by an amount equal to the heat absorbed or emitted divided by the thermodynamic temperature. It is measured in joules per kelvin
   See also law of thermodynamics
2. lack of pattern or organization; disorder

Etymology: 19th Century: from en-² + -trope