Im*per"me*a*ble (?), a. [Pref. im- not + permeable: cf. F. imperm'eable, L. impermeabilis.]
Not permeable; not permitting passage, as of a fluid. through its substance; impervious; impenetrable; as, India rubber is impermeable to water and to air.
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Im*per"me*a*ble*ness, n. --
Im*per"me*a*bly, adv.
© Webster 1913.