statistical mechanics

WordReference Random House Unabridged Dictionary of American English © 2025

statis′tical mechan′ics, [Physics, Chem.] (used with a sing. v.)

1. Physics the science that deals with average properties of the molecules, atoms, or elementary particles in random motion in a system of many such particles and relates these properties to the thermodynamic and other macroscopic properties of the system. Also called statis′tical phys′ics, statis′tical thermodynam′ics. Cf. Maxwell-Boltzmann statistics, quantum statistics. 

• 1880–85

Collins Concise English Dictionary © HarperCollins Publishers::

statistical mechanics noun

1. (functioning as singular) the study of the properties of physical systems as predicted by the statistical behaviour of their constituent particles