from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Incapable of being penetrated: a material impervious to water.
  • adj. Incapable of being affected: impervious to fear.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. unaffected or unable to be affected by
  • adj. preventative of any penetration; impenetrable, impermeable, particularly of water
  • adj. immune to damage or effect

from the GNU version of the Collaborative International Dictionary of English

  • adj. Not pervious; not admitting of entrance or passage through.

from The Century Dictionary and Cyclopedia

  • Not pervious; not to be passed through or penetrated; impermeable; impenetrable: as, a substance impervious to moisture.
  • Synonyms Impenetrable, impassable, pathless.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. not admitting of passage or capable of being affected


from The American Heritage® Dictionary of the English Language, 4th Edition

From Latin impervius : in-, not; see in-1 + pervius, pervious; see pervious.

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Latin impervius ("cannot be passed through"), from in- ("not") + pervius ("letting things through")


  • Modest increases in impervious surface due to construction of cottages can in most cases easily be offset by modest removal of impervious surfaces on affected lots, and/or disconnection of downspouts from pipes that discharge runoff to streets.

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  • We, the English, as you can see, are of average height, smoke a pipe, carry a rolled umbrella, go to the best schools, yet remain impervious to knowledge.

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  • With the assistance of such guides, nothing could remain impervious or inaccessible; resistance was fatal; flight was impracticable; and the patient submission of helpless innocence seldom found mercy from the Barbarian conqueror.

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  • Fletcher: "We need to go back and reduce the amount of what we call impervious surface, the amount of pavement and roofs that won't absorb water.

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  • All of nature’s indicators speak of global strain, and yet we the relatively affluent remain impervious to it.

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  • "Inner-directed" could be defined as impervious to outside criticism, advice or even reality.

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  • New technology, a changing marketplace, and the emergence of a global economy are factors to which no nation and no economic system can remain impervious.

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  • In the execution of my recommendations in every department of the service he was always eager, capable, in one word impervious against every temptation to ease, unwearied by any labour, fearless of every danger.

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  • In metro Atlanta, the area blanketed by hard, man-made solids such as asphalt - what experts call impervious surface - grew by 20 percent over the past decade, the AJC's analysis shows, replacing acres of absorbent grasslands and forests. - News

  • These surfaces are usually impervious, meaning that water runs off of them without being absorbed into the soil.

    Pollution~ urban and suburban areas


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