thermalization

This term is used almost exclusively within the specialized registers of thermodynamics, statistical mechanics, and quantum physics. It describes a transition from a non-equilibrium state to a state of equilibrium, emphasizing the redistribution of energy until a uniform temperature is achieved across a system.

Because it describes a continuous physical process or a conceptual state of evolution, it is treated as an uncountable noun. It does not refer to a discrete event that can be counted, but rather to the phenomenon of reaching thermal balance.