quasi-static process[¦kwä·zē ′stad·ik ′prä·səs]
equilibrium process, the infinitely slow transition of a thermodynamic system from one equilibrium state to another, in which the physical state of the system at any given moment differs infinitesimally from the equilibrium state. Equilibrium in a system in a quasi-static process is established many times more rapidly than change in the physical parameters of the system. Any quasi-static process is reversible. Quasi-static processes play an important role in thermodynamics, since thermodynamic cycles including only quasi-static processes yield maximum work values. The term "quasi-static process" was proposed in 1909 by C. Caratheodory.