impermeable

IPA/ɪmˈpɜːmiəbl/
IPA/ɪmˈpɜːrmiəbl/

impermeable — adjective

  • impermeablepositive
  • more impermeablecomparative
  • most impermeablesuperlative

1. describing a material or surface that liquids and gases cannot pass through — fo

1.adjectiveB2
Definition

describing a material or surface that liquids and gases cannot pass through — for example, a plastic sheet that blocks water, or a clay layer that traps gas underground.

Example

The raincoat is made of an impermeable fabric that keeps you completely dry.

collocation: impermeable fabric

Engineers placed an impermeable clay layer to keep water out of the basement.

pattern: impermeable [material] + purpose clause

Common collocations
  • impermeable layer
  • impermeable membrane
  • impermeable barrier
  • impermeable surface
  • impermeable to water
  • impermeable to gas
  • impermeable to air
  • highly impermeable
  • relatively impermeable
Synonyms
  • waterproof

    more common in everyday language; specifically about water, not other fluids or gases

  • hermetically sealed

    much stronger — means perfectly airtight, often used for scientific containers

  • impervious

    broader — can also describe resistance to damage, criticism, or influence

Antonyms
  • permeable

    the direct opposite — allows fluids to pass through

  • porous

    describes a material with tiny holes that let air or water through slowly

Grammar Patterns

impermeable + noun

impermeable to + noun

Usage Note

More formal and technical than 'waterproof'. While 'waterproof' applies only to water, 'impermeable' can describe resistance to any liquid or gas. The subject is usually a material, layer, or barrier — not an object's function. Frequently used in construction, geology, and manufacturing contexts.

Common Mistakes

This bottle is impermeable.
This bottle is made of impermeable plastic.
'impermeable' describes the material, not the container itself.
The jacket is impermeable.
The jacket has an impermeable outer layer.
in everyday English, 'waterproof' is more natural for finished products; 'impermeable' describes the material or layer.

Word family

Synonym discussion

Sense: adjective/1

'Waterproof' is the most common everyday word — it specifically prevents water from getting in, but says nothing about gases or other liquids (a waterproof watch may still let air through). 'Impermeable' is more technical and broader: it covers any fluid (liquid or gas). 'Impervious' overlaps with 'impermeable' for physical barriers but is also used figuratively (impervious to criticism). 'Airtight' refers specifically to gases (an airtight container keeps air out or in). 'Sealed' describes the state of being closed, not the material property itself — a sealed jar keeps contents fresh because of the seal, not because the glass is impermeable. Use 'impermeable' when you want to stress the material's inherent resistance to any fluid, especially in technical or scientific writing.

waterproof ↗impervious ↗airtight ↗sealed ↗

Common collocations

Nouns

  • impermeable layer
  • impermeable membrane
  • impermeable barrier
  • impermeable material
  • impermeable surface
  • impermeable rock
  • impermeable fabric

Adverbs

  • highly impermeable
  • completely impermeable
  • relatively impermeable
  • virtually impermeable

Phrases

  • impermeable to water
  • impermeable to gas
  • impermeable to air
  • impermeable to liquids

Prepositions

  • impermeable to

Etymology

LatinFrenchEnglish

Comes from Latin 'impermeabilis', formed by adding the negative prefix 'in-' to 'permeabilis' (passable). 'Permeabilis' comes from 'permeare' — 'per-' (through) plus 'meare' (to pass or go). English borrowed the word through French 'imperméable' in the 1700s, originally as a term in physics and chemistry.