Permeability, permeable and semipermeable may refer to:
- Permeability (electromagnetism), the degree of magnetization of a material in response to a magnetic field
- Vacuum permeability, permeability of free space or magnetic constant, a physical constant, the value of magnetic permeability in a classical vacuum
- Permeability (earth sciences), a measure of the ability of a material (such as rocks) to transmit fluids
- Semipermeable membrane, a membrane which will allow certain molecules or ions to pass through it by diffusion
- Permeability (nautical), in ship design, the percentage of empty space in a compartment or tank
- Permeation of a gas or vapor through a solid substance
- Vascular permeability, the movement of fluids and molecules between the vascular and extravascular compartments
- Permeability (spatial and transport planning), the extent to which the layout of urban forms enables people or vehicles to move in different directions
- Permeability (foundry sand), is a test of the venting characteristics of a rammed foundry sand
- Hydraulic conductivity the permeability of soil for water