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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
From the Late Latin word impermeābilis, dating back to 1690-1700. 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. 2018.
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Examples from the Web for impermeable
Contemporary Examples
Historical Examples
  • He was so gross, so impermeable to all the subtler issues of being.

    Tales of Space and Time Herbert George Wells
  • You could not culturalize the impermeable texture of their vulgarity.

    The Freelands John Galsworthy
  • It is because faith has this origin that it is, in a sense, "impermeable to experience."

  • A word that has reclassified in an entertaining manner our impermeable and eternal ignorance.

    The Roycroft Dictionary Elbert Hubbard
  • The wing rose by means of a crank and a moveable piston, and was covered by impermeable taffeta.

    The Romance of Leonardo da Vinci

    Dmitry Sergeyevich Merezhkovsky
  • Jean Cornbutte contrived to surround this part of the pipe with some metallic canvas, which is impermeable by heat.

    A Winter Amid the Ice Jules Verne
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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