- a thermodynamic measure of the amount of energy unavailable for useful work in a system undergoing change
- a measure of the degree of disorder in a substance or a system: entropy always increases and available energy diminishes in a closed system, as the universe
- in information theory, a measure of the information content of a message evaluated as to its uncertainty
- a process of degeneration marked variously by increasing degrees of uncertainty, disorder, fragmentation, chaos, etc.; specif., such a process regarded as the inevitable, terminal stage in the life of a social system or structure
Origin of entropy
German entropie, arbitrary use (by R. J. E. Clausius, 1822-88, German physicist) of Classical Greek entrop?, a turning toward, as if from German en(ergie), energy + Classical Greek trop?, a turning: see trope
