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

The team then married this data with land-use data showing where in LA County there’s good tree cover, which reflects heat, and where there are impermeable surfaces like pavement, which absorb it. —Matt Simon, WIRED, 9 May 2024

American cities like Los Angeles and Pittsburgh have been rolling out something similar: Taxes on the amount of impermeable area on a property, like concrete, that incentivize landowners to develop gardens and other green spaces instead. —Matt Simon, WIRED, 22 Apr. 2024

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