Editing Entropy (section)

=== Standard textbook definitions ===
The following is a list of additional definitions of entropy from a collection of textbooks:
* a measure of [[energy dispersal]] at a specific temperature.
* a measure of disorder in the universe or of the availability of the energy in a system to do work.<ref>{{cite book|last1=Gribbin|first1=John|editor1-last=Gribbin|editor1-first=Mary|title=Q is for quantum : an encyclopedia of particle physics|date=1999|publisher=Free Press|location=New York|isbn=978-0-684-85578-3|url=https://archive.org/details/qisforquantumenc00grib}}</ref>
* a measure of a system's [[thermal energy]] per unit temperature that is unavailable for doing useful [[work (thermodynamics)|work]].<ref>{{cite web|title=Entropy: Definition and Equation|url=https://www.britannica.com/EBchecked/topic/189035/entropy|website=Encyclopædia Britannica|access-date=22 May 2016}}</ref>

In Boltzmann's analysis in terms of constituent particles, entropy is a measure of the number of possible microscopic states (or microstates) of a system in thermodynamic equilibrium.