adjective
- permeable only to certain small molecules: a semipermeable membrane.
adjective
- (esp of a cell membrane) selectively permeable
adj.1873, from semi- + permeable. Translating German halbdurchlässig. adj.
- Partially permeable.
- Allowing passage of certain, especially small, molecules or ions but acting as a barrier to others. Used of biological and synthetic membranes.