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 of impermeable

• impervious
• dense
• close
• impenetrable
• impassable
• impregnable
• thick

Examples of impermeable in a Sentence

an impermeable layer of rock

a fabric impermeable to moisture

Recent Examples on the Web

Charlotte has been blessed to grow at a fast rate, but our expansion has removed green spaces with impermeable pavement and buildings. — Charlotte Observer, 6 Oct. 2026

Sign up for the newsletter When the rain does fall, Kabul’s hard, impermeable surfaces mean the water doesn’t replenish aquifers, but instead sweeps through the city as flash floods, destroying homes, killing people and rolling away. — Laura Paddison, CNN Money, 6 Oct. 2026

The method works best with an opaque, impermeable tarp in hot, sunny weather, while cooler conditions may take longer and require cleanup after removal. — Michelle Mastro, Martha Stewart, 26 Sep. 2026

But as the AfD gains clout through regional elections, the debate within the CDU over exactly how impermeable that firewall should be is also intensifying. — Anna Noryskiewicz, CBS News, 18 Sep. 2026

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