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“semipermeable”
semipermeable (adjective), more semipermeable, most semipermeable
Partially or selectively penetrable: Such materials as membranes are semipermeable in that they allow certain liquids or gases to pass through, but not other substances.
(Latin: a storeroom, a chamber, a closet; by extension, of or pertaining to a cell, a microscopic protoplasmic mass made up of a nucleus enclosed in a semipermeable membrane)