Definition of impermeable in US English:



  • 1Not allowing fluid to pass through.

    ‘an impermeable membrane’
    • ‘He developed a mattress cover which is free of the suspected chemicals and impermeable to gasses.’
    • ‘Lacquer, the sap of a tree, has to be applied in thin layers over a long period to build up a surface that is impermeable to liquids.’
    • ‘It creates a flexible seal that is completely impermeable to water, dust, insects, rodents and vibration.’
    • ‘Condoms are essentially impermeable to particles the size of STD pathogens including the smallest sexually transmitted virus.’
    • ‘The authors conclude that applying a mattress cover that is impermeable to house-dust mite allergen on the beds of children and their parents reduces night cough in the second year of life.’
    • ‘Because this layer should permit passage of fluid, impermeable dressings are not recommended.’
    • ‘However, the inside lining of the heart is smooth and impermeable to the oxygen tied to the red cells.’
    • ‘Local media have questioned some projects, such as draining water from the chain of lakes outside the Old Summer Palace ruins to install an impermeable membrane that would stop water from seeping into the ground.’
    • ‘The plastic is hydrophobic and thus impermeable to ions and water.’
    • ‘Do health care workers really need a single fabric that is 100% impermeable to bloodborne viruses and bacteria to be used in every surgical procedure?’
    • ‘The gasket has a core that is impermeable to liquids, with a first side and a second side opposite the first side.’
    • ‘The resulting concrete is said to be impermeable to the migration of water or waterborne chemicals.’
    • ‘This will render the topo impermeable, yet still allow you to write notes on it with a ballpoint pen.’
    • ‘The sea snake's skin is impermeable to water but they can extract 20% of their oxygen needs through their skin from oxygen dissolved in seawater.’
    • ‘I had noticed that gumboots were impermeable to water from the outside, and deduced that they must also be impermeable from the inside.’
    • ‘This may involve professional help, as your roof has to be strong enough to support the mat of plants, and it will also require an impermeable membrane underneath.’
    • ‘Some have succeeded in making their cell walls impermeable to antibiotics.’
    • ‘Also, old clay pots can build up enough fertilizer and salts to make them impermeable to air and water.’
    • ‘But even watertight concrete is not impermeable to the passage of moisture.’
    • ‘The material must be continuous and virtually impermeable to air.’
    1. 1.1 Not liable to be affected by pain or distress; insusceptible or imperturbable.
      ‘women who appear impermeable to pain’


Late 17th century: from French imperméable, or from late Latin impermeabilis, from in- ‘not’ + permeabilis (see permeable).