Definition
Zeroeth Law of Thermodynamics
The Zeroeth Law of Thermodynamics states that if two thermodynamic systems are each in thermal equilibrium with a third system, then they are in thermal equilibrium with each other.
Overview
This law establishes thermal equilibrium as a transitive relationship, providing the theoretical foundation for the definition of temperature and the use of thermometers. If multiple systems are in equilibrium, they share the same temperature.