membrane
n.-
1 biological lining (n.) C1 Advanced Technical Sciencea thin layer of skin or tissue that covers or connects parts of the body.
a thin layer of tissue that covers a surface, lines a cavity, or divides a space or organ in an animal or plant.
ExampleThe eardrum is a thin membrane that vibrates when sound waves hit it.
ExampleThe mucous membrane lining the respiratory tract serves as a primary defense mechanism by trapping inhaled pathogens and particles.
UsageOften used with 'mucous', 'cell', or 'plasma'.
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2 synthetic filter (n.) C1 Advanced Technical Sciencea thin sheet of material used to filter liquids or gases.
a thin, semi-permeable material used in industrial or laboratory processes to separate substances in a fluid.
ExampleThe water filter uses a special membrane to remove salt from the ocean water.
ExampleAdvanced desalination plants utilise reverse osmosis membranes to extract potable water from high-salinity sources with high efficiency.
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3 historical parchment (n.) C2 Proficiency Archaic Technicala single sheet of parchment used in an old scroll or document.
a piece of parchment or vellum forming a single leaf or part of a larger roll.
ExampleThe historian carefully unrolled the ancient membrane to read the text.
ExampleThe medieval tax records were meticulously inscribed across several membranes of sheepskin, which were then stitched together into a continuous roll.
Teacher's tipThis sense is rare and restricted to historical or archival contexts; modern speakers use 'sheet' or 'page'.
Late Middle English, borrowed from Latin membrāna (“skin or membrane that covers parts of the body”), from membrum (“a limb or member of the body”) + -āna. Doublet of membrana.