1) Permeability 2) Permeableness 3) Perviousness 1) Perviousness 
• (n.) The quality of being penetrable; susceptibility of being penetrated, entered, or pierced.
the ability of a material to be traversed NOTE - This term should not be used as a synonym for radiation quality.
(pen″ә-trә-bil´ĭ-te) the ability of x-rays to penetrate matter.
Pen`e·tra·bil'i·ty noun [ Confer French pénétrabilité .] The quality of being penetrable; susceptibility of being penetrated, entered, or pierced. Cheyne. 
[n] - the permeability of something that can be penetrated by a liquid
perviousness noun the quality of being penetrable (by people or light or missiles etc.)