1) Permeable 2) Selectively permeable 1) Permeable 
Freely permeable to water (or other solvent) but relatively impermeable to solutes. Depending on the context, it has been used to imply impermeability to all solutes except very small uncharged molecules (e.g., a cell membrane), or merely impermeability to very large molecules such as proteins (e.g., a capillary membrane). ... (05 Mar 2000) ... 
(sem″e-pur´me-ә-bәl) permitting passage only of certain molecules.
Type: Term Pronunciation: sem′ē-per′mē-ă-bĕl Definitions: 1. Freely permeable to water (or other solvent) but relatively impermeable to solutes. Depending on the context, it has been used to imply impermeability to all solutes except very small uncharged molecules (a cell membrane), or merely impermeability to very l...
[adj] - (of a membrane) selectively permeable
adjective (of a membrane) selectively permeable