third law of thermodynamics

WordReference Random House Unabridged Dictionary of American English © 2025

third′ law′ of thermodynam′ics. 

1. Thermodynamics See under law of thermodynamics (def. 1).

WordReference Random House Unabridged Dictionary of American English © 2025

law′ of thermodynam′ics, 

1. Thermodynamics any of three principles variously stated in equivalent forms, being the principle that the change of energy of a thermodynamic system is equal to the heat transferred minus the work done (first law of thermodynamics,) the principle that no cyclic process is possible in which heat is absorbed from a reservoir at a single temperature and converted completely into mechanical work (second law of thermodynamics,) and the principle that it is impossible to reduce the temperature of a system to absolute zero in a finite number of operations (third law of thermodynamics). 
2. Thermodynamics See zeroth law of thermodynamics.