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

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

The Chinese-Russian relationship is not impermeable, and the United States should not shy away from proactive measures to exploit its fissures. —Andrea Kendall-Taylor, Foreign Affairs, 3 May 2021

Word History

Etymology

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

First Known Use

1661, in the meaning defined above

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