The term entropy was introduced in 1865 by Rudolf Clausius from a Greek word meaning "transformation". It characterizes the degree of disorganization, or unpredictability of the information content of a system.
For example, in physics, entropy is a thermodynamic quantity associated with a particle system. In astrophysics, the entropy of black holes has been introduced. And in statistical physics: entropy of a gas of bosons, fermionic entropy.
