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

The impermeable seed coat strategy generally helps survival of the species by making sure all of a season’s crop don’t germinate in the same year. —Paul Cappiello, Louisville Courier Journal, 21 Nov. 2025

The discovery could enable large-scale use of impermeable coatings once limited by graphene’s scalability issues. —Aamir Khollam, Interesting Engineering, 12 Nov. 2025

The company says the finalized Bio foil provides the full and appropriate level of impermeable barrier protection and odorless performance. —New Atlas, 9 Oct. 2025

Chocolate brown stripes punctuate a light charcoal gray background, and the low-pile weave made from recycled polyester gives it an impermeable, easy-to-clean surface. —Julia Harrison, Architectural Digest, 6 Oct. 2025

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