Not permeable; not permitting the passage of substances ( e.g., liquids, gases) or heat through a membrane or other structure. SYN: impervious. [L. im- permeabilis, not to be passed through]
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im·per·me·able (')im-'pər-mē-ə-bəl adj not permitting passage (as of a fluid) through its substance <the plasma membrane of a red blood cell is relatively \impermeable to sodium and calcium ions>
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im·per·me·a·ble (im-purґme-ə-bəl) [in-2 + per- + meare to move] not permitting passage, as of fluid.Medical dictionary. 2011.