Definition: The ability of water to flow through a soil is referred to as the soil's permeability. As you can probably guess, the permeability of gravel is higher than that of clay.
Permeability is typically determined in the lab by application of Darcy's law under steady state conditions or, more generally, by application of various solutions to the diffusion equation for unsteady flow conditions.
Examples:
The greater the permeability, the more rapidly the liquid could reach an underground soil layer.
