law of nature, law - a generalization that describes recurring facts or events in nature; "the laws of thermodynamics"

second law of thermodynamics - a law stating that mechanical work can be derived from a body only when that body interacts with another at a lower temperature; any spontaneous process results in an increase of entropy

third law of thermodynamics - law stating that the entropy of a substance approaches zero as its temperature approaches absolute zero

zeroth law of thermodynamics - the law that if two bodies are in thermal equilibrium with a third body then the first two bodies are in thermal equilibrium with each other

natural philosophy, physical science, physics - the science of matter and energy and their interactions

conservation of energy, first law of thermodynamics, law of conservation of energy - the fundamental principle of physics that the total energy of an isolated system is constant despite internal changes