What is the saturation pressure?

Vapor pressure is a measurement of the amount of moisture in the air. It is technically the pressure of water vapor above a surface of water. When air reaches the saturation vapor pressure, the water vapor in it will condense. At this time, the dew point temperature is the same as the air temperature. read more

Definition of saturation pressure. : the pressure of a vapor which is in equilibrium with its liquid (as steam with water); specifically : the maximum pressure possible by water vapor at a given temperature. read more

And Saturation Pressure can be defined as the pressure corresponding to a temperature called saturated temperature (say T0) at which the vapour pressure of the mixture equals the atmospheric pressure. (The system is said to have reached its boiling point.) Lets, understand it from the graph above(from wiki). read more