• synonyms


[im-pur-mee-uh-buh l]
See more synonyms for impermeable on Thesaurus.com
  1. not permeable; impassable.
  2. Chemistry, Geology. (of porous substances, rocks, etc.) not permitting the passage of a fluid through the pores, interstices, etc.
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Origin of impermeable

From the Late Latin word impermeābilis, dating back to 1690–1700. See im-2, permeable
Related formsim·per·me·a·bil·i·ty, im·per·me·a·ble·ness, nounim·per·me·a·bly, adverb
Can be confusedimpermeable impervious
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words


Examples from the Web for impermeability

Historical Examples

  • It is only when in combination that it exhibits this impermeability to the obscure rays.

    The Glaciers of the Alps

    John Tyndall

  • The impermeability of plastic clay to water is a characteristic which is important for many purposes.

  • The fused portion fills the pores or interstices of the material, making—when cold—a ware of great strength and impermeability.

  • The integrity and impermeability of this asphalt coat are quite as vital as constant saturation.

British Dictionary definitions for impermeability


  1. (of a substance) not allowing the passage of a fluid through interstices; not permeable
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Derived Formsimpermeability or impermeableness, nounimpermeably, 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

Word Origin and History for impermeability



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

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Online Etymology Dictionary, © 2010 Douglas Harper

impermeability in Medicine


  1. Impossible to permeate; not permitting passage.
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Related formsim•per′me•a•bili•ty null n.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

impermeability in Science


  1. 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.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.