ETYM Latin permeabilis: cf. French perméable. Related to Permeate.
Allowing (especially liquids) to pass or diffuse through.

Množina: permeable rocks

Rock that allows water to pass through it. Rocks are permeable if they have cracks or joints running through them or if they are porous, containing many interconnected pores. Examples of permeable rocks include limestone (which is heavily jointed) and chalk (porous).
Unlike impermeable rocks, which do not allow water to pass through, permeable rocks rarely support rivers and are therefore subject to less erosion. As a result they commonly form upland areas (such as the chalk downs of SE England, and the limestone Pennines of N England).