semipermeable membrane
1
4.6
- noun
- /ˌsɛmiˈpɜrmiəbl ˈmɛmˌbreɪn/
- Specialized
:
membrana semipermeable
- The filter works by using a semipermeable membrane that allows water to pass while blocking larger contaminants.
Examples
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In the experiment, the semipermeable membrane separated the saltwater from the freshwater, demonstrating osmosis.
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The traditional tablet structure is replaced by a tablet-sized structure made up of a semipermeable membrane that encloses the active drug and the osmotic driving agent.
Academic text (2011) -
PHOTO (COLOR): EDR uses voltage potential to force contaminants through semipermeable membranes to filter out dissolved ions from water.
Academic text (2003) -
Cells contain a semipermeable membrane that regulates the movement of substances into and out of the cell.
How Permeable
Surface Forms
Morphology
The meaning 'a membrane that allows certain molecules or ions to pass through but not others' is directly and compositionally derived from 'semipermeable' (permits specific substances to pass) modifying 'membrane' (a thin layer). This follows a common adjective + noun pattern and is cross-linguistically transparent, so a B1 learner who knows both constituents can infer the MWE meaning.
Etymology
Semipermeable membrane paints a picture of a thin skin with tiny holes that only let some things pass. The parts semi means 'partly' and permeable means 'can be passed', so the idea is a skin that is only partly open. That's why it means 'lets certain molecules pass but not others'.