An Etymological Dictionary of Astronomy and Astrophysics

A vapor at the pressure and temperature at which it can exist in dynamical equilibrium with its liquid. Any compression of its volume at constant temperature causes it to condense to liquid at a rate sufficient to maintain a constant pressure. The term “saturated” is a misnomer, since it does not have the same meaning as a → saturated solution in chemistry. There is no question of one substance being dissolved in another.

Etymology (EN): → saturate; → vapor.