impermeable

1 of 2

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

impermeability

2 of 2

noun

im·​permeability (¦)im 

əm+

: the quality or state of being impermeable

Synonyms of impermeable

Adjective

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

Examples of impermeable in a Sentence

Adjective

an impermeable layer of rock

a fabric impermeable to moisture

Recent Examples on the Web

Adjective

Dry waterproofing technology, which is basically like an invisible, impermeable sock liner. —Olivia Young, Travel + Leisure, 29 May 2026

The spongy material is mostly made of air, yet nearly impermeable to both air and liquid. —Brandee Gruener, Southern Living, 29 Apr. 2026

The outer layer hardened and became impermeable. —Catherina Gioino, Fortune, 11 Apr. 2026

Oil and gas infuse the pores of sandstone; layers of impermeable caprock trap it inside. —Jeffrey Marlow, New Yorker, 5 Apr. 2026

Word History

Etymology

Adjective

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

First Known Use

Adjective

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