NPSH or Net Positive Suction Head is a measure of the minimum pressure at the inlet required to prevent cavitation in the pump.
Refers to the speed of the medium.
The pressure that can be measured at the inlet of the pump.
At the pressure that the medium switches to steam.
Density or volume mass is a SI unit and is a measure of the density of a specific substance, ie mass per unit volume. A synonym for density that can sometimes occur is specific importance.
Acceleration of gravity
Is a constant that is an expression of how much gravity the earth's gravity affects the medium. The constant varies depending on where on earth you are.