impermeable

American  

[im-pur-mee-uh-buhl] / ɪmˈpɜr mi ə bəl /

adjective

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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impermeable British  

/ ɪmˈpɜːmɪəbəl /

adjective

1. (of a substance) not allowing the passage of a fluid through interstices; not permeable

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impermeable Scientific  

/ ĭm-pûr′mē-ə-bəl /

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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Other Word Forms

• impermeability noun
• impermeableness noun
• impermeably adverb

Etymology

Origin of impermeable

From the Late Latin word impermeābilis, dating back to 1690–1700. See im- ², permeable

Compare meaning

How does impermeable compare to similar and commonly confused words? Explore the most common comparisons:

• permeable vs. impermeable

Explanation

If you have a waterproof raincoat, you could say that your coat is impermeable to the rain. Something that is impermeable does not allow water or liquid to pass through it. Made up of the prefix im-, meaning “not,” and the adjective permeable, meaning “allowing to pass through,” impermeable is used in much the same way as impervious or impenetrable. However, more so than these words, impermeable is especially associated with liquids and is often used in a scientific or technical context. Some gadgets, like waterproof watches and underwater cameras, are designed to be impermeable.

Example Sentences

"We come to live in bubbles, impermeable to one another," he said.

From BBC • Apr. 17, 2026

One of the reed-covered mounds was located directly above a point where freshwater was rising through a break in the impermeable layer beneath the lake.

From Science Daily • Mar. 21, 2026

“Europe needs to make itself impermeable to every interference” by outside powers, whether the U.S. or Russia, he said.

From The Wall Street Journal • Jan. 19, 2026

Roberts said that Chiquita Canyon was far behind schedule with the installation of a large impermeable cover, which was intended to suppress odors.

From Los Angeles Times • Aug. 30, 2024

Those that come close suddenly change direction before hitting her glove, bouncing off as though she is surrounded by something invisible and impermeable.

From "The Night Circus" by Erin Morgenstern