impermeable

adjective

im·​per·​me·​able (ˌ)im-ˈpər-mē-ə-bəl 

: not permitting passage (as of a fluid) through its substance

broadly : impervious

impermeability

(ˌ)im-ˌpər-mē-ə-ˈbi-lə-tē 

noun

Synonyms

• impassable
• impassible
• impenetrable
• impervious
• impregnable

Examples of impermeable in a Sentence

an impermeable layer of rock

a fabric impermeable to moisture

Recent Examples on the Web

Surface treatments can help make paper—which naturally sops up moisture from the air that could affect the device built on top—relatively impermeable. —IEEE Spectrum, 29 Jan. 2013

Pepe has been Portugal’s bedrock for almost two decades, a scratching, impermeable presence who won 141 caps for his country, and was central to their first major trophy at Euro 2016. —Jacob Whitehead, The Athletic, 8 Aug. 2024

Clay deposits, forming an impermeable layer, result in waterlogged soil. —David Bressan, Forbes, 31 Oct. 2024

There is a retention pond to capture heavy rain, minimum impermeable surfaces, and any runoff is directed to trees and plants. —Jennifer Castenson, Forbes, 22 Oct. 2024

Word History

Etymology

Late Latin impermeabilis, from Latin in- + Late Latin permeabilis permeable

First Known Use

1661, in the meaning defined above

Rhymes for impermeable

• permeable
• semipermeable

Kids Definition

impermeable

adjective

im·​per·​me·​able (ˈ)im-ˈpər-mē-ə-bəl 

: not permitting passage (as of a fluid) through the material of which it is made

impermeability

(ˌ)im-ˌpər-mē-ə-ˈbil-ət-ē 

noun

Medical Definition

impermeable

adjective

im·​per·​me·​able (ˈ)im-ˈpər-mē-ə-bəl 

: not permitting passage (as of a fluid) through its substance

the plasma membrane of a red blood cell is relatively impermeable to sodium and calcium ions

impermeability

(ˌ)im-ˌpər-mē-ə-ˈbil-ət-ē 

noun

plural impermeabilities