Entropy (Greek: en = in and tropos = way/means) can have one of several meanings:

• Thermodynamic entropy in the context of chemistry, physics, and thermodynamics, is a measure of the amount of energy in a physical system which cannot be used to do mechanical work.
• Entropy in the context of probability theory, statistics, and information theory, measures the amount of information that is contained in a random variable or other unknown quantity.
• In the theory of metric spaces in mathematics, entropy numbers are used to measure the dimension of sets (and in particular fractals).
• Entropy (board game) refers to two board games known under the name Entropy, invented by Eric Solomon (1977) or Augustine Carreno (1994).
• "Entropy" is a song on The 'b' Album by Moxy Früvous
• Entropy (anonymous data store) is a decentralized, peer-to-peer communication network designed to be resistant to censorship.
• Entropy is a measure of biodiversity in the study of biological ecology.
• Entropy (linguistics) .
• Entropy is the name of a non-profit student organization for the advancement of electronic music at the Helsinki University of Technology
• Entropy is the name of a Renderman-Interface compliant 3D Renderer that was developed by Berkely software company Exluna until further development was halted as part of the settlement of a patent lawsuit filed by Pixar. Exluna were subsequently acquired by Nvidia Corporation to develop a hardware-accelerated renderer that is able to use Nvidia GPU's to accelerate the rendering process.