What does impermeability mean?
Impermeability is the quality of being unable to allow water or another liquid to pass through. In technical contexts, it describes a property of materials, membranes, coatings, and structures: a waterproof fabric, for example, has impermeability because it prevents water from penetrating it. The term can also be used figuratively to describe resistance to outside influence, interference, or scrutiny. Although “impermeability” is closely related to “imperviousness,” it is especially associated with the physical capacity of a material to block liquid. The word is most useful in scientific, engineering, environmental, and product-description contexts, where precision about the barrier or material being discussed matters. Its formation reflects the contrast between “permeable,” meaning able to allow passage through, and “impermeable,” meaning unable to do so.
nounThe quality of being impermeable, especially the resistance of a material or barrier to the passage of water or another liquid. It can also refer more generally to resistance to penetration or influence.
- The quality or condition of being impermeable, especially the resistance of a material to the passage of water or another liquid.
- More generally, resistance to penetration, influence, or disclosure.
"The coating gives the fabric a high degree of impermeability while remaining lightweight."
"The impermeability of the rubber seal prevented any water from entering the chamber."
"The company's defenses were characterized by their impermeability to outside influence."
Used when referring to the separate impermeability properties of different materials, objects, or barriers.
"The tests compared the impermeabilities of several waterproof membranes."
Impermeability is what turns cloth, membranes, and containers into barriers that keep unwanted water out.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does impermeability come from?
The word was formed in English by adding the suffix “-ity” to “impermeable,” producing a noun that names the corresponding quality. “Impermeable” comes through Latin from the roots per-, meaning “through,” and meare, meaning “to pass,” with the negative prefix im- indicating that passage is prevented. Related English words include “permeable,” “permeability,” and “impervious,” all of which reflect the same Latin root concerned with passing through.
How impermeability is actually used
The technical sense, concerning materials that do not allow liquids or gases to pass through, is most common. The broader sense of being unaffected by outside influence is more figurative and is usually found in formal writing.
Easily confused with impermeability
Impermeability is the measurable property of a material or barrier, whereas imperviousness can describe resistance to liquids, gases, influence, or attention more generally.