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

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Etymology

Origin of impermeable

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

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Compare meaning

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

• permeable vs. impermeable

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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

See Examples For:

impermeable

State officials estimated the costs at $4,100 per acre of paved or impermeable surface for those that decide to help fund local stormwater projects, and said the costs for other options could be considerably higher.

From Los Angeles Times ● Jul. 29, 2026

"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

Although scientists once believed that the placenta was a tight, impermeable barrier separating mother and child, that’s not true.

From The Wall Street Journal ● Nov. 4, 2025

But it is illusion to think that there is anything fragile about the life of the earth; surely this is the toughest membrane imaginable in the universe, opaque to probability, impermeable to death.

From "The Lives of a Cell" by Lewis Thomas

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