* Permeability is a measure of how easily fluids (liquids or gases) can flow through a porous material. It's directly related to the size and interconnectedness of the pores within the material.

Let's look at the other terms:

* Capacity generally refers to the total amount of something a material can hold. In the context of fluids, it might refer to the total volume of fluid a material can absorb.

* Competence in geology often refers to a rock's ability to withstand stress and deformation without fracturing. It's not directly related to fluid flow.

In summary: Permeability is the specific property that quantifies a material's ability to transmit fluids through its pores.