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[im-pur-mee-uh-buh l] /ɪmˈpɜr mi ə bəl/
not permeable; impassable.
Chemistry, Geology. (of porous substances, rocks, etc.) not permitting the passage of a fluid through the pores, interstices, etc.
Origin of impermeable
1690-1700; < Late Latin impermeābilis. See im-2, permeable
Related forms
impermeability, impermeableness, noun
impermeably, adverb
Can be confused
impermeable, impervious. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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British Dictionary definitions for impermeable


(of a substance) not allowing the passage of a fluid through interstices; not permeable
Derived Forms
impermeability, impermeableness, noun
impermeably, adverb
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for impermeable

1690s, from French imperméable, from Late Latin impermeabilis, from assimilated form of in- "not, opposite of" (see in- (1)) + permeabilis (see permeable).

Online Etymology Dictionary, © 2010 Douglas Harper
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impermeable in Medicine

impermeable im·per·me·a·ble (ĭm-pûr'mē-ə-bəl)
Impossible to permeate; not permitting passage.

im·per'me·a·bil'i·ty or im·per'me·a·ble·ness n.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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impermeable in Science
Relating to a material through which substances, such as liquids or gases, cannot pass. Some substances, such as some types of contact lenses, are permeable to gas but impermeable to liquid.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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