A Permeability

1. The property of being permeable.
2. The rate of flow of a fluid through a porous material.
3. (geology) A measure of the ability of a rock to transmit fluids (such as oil or water).
4. (physics) A quantitative measure of the degree of magnetization of a material in the presence of an applied magnetic field (measured in newtons per ampere squared in SI units). Permeability (electromagnetism) - Wikipedia