impervious

adjective

im·​per·​vi·​ous (ˌ)im-ˈpər-vē-əs 

1

a

: not allowing entrance or passage : impenetrable

a coat impervious to rain

b

: not capable of being damaged or harmed

a carpet impervious to rough treatment

2

: not capable of being affected or disturbed

impervious to criticism

imperviously adverb

imperviousness noun

Did you know?

Finding your way through some words’ etymologies can lead to surprising discoveries of origins that seemingly have little to do with their modern-day meanings. Impervious, which entered English in the early 1600s, is not one of those words—its history is entirely straightforward. The Latin ancestor of impervious is impervius, which adds the prefix im-, meaning “not,” to pervius, meaning “passable or penetrable.” Pervius in turn comes from per, meaning “through,” and via, meaning “way.” Impervious, it follows, describes things that don’t allow a way through something, whether literally (as in “asphalt, concrete, and other surfaces that are impervious to rain”) or figuratively (as in “impervious to criticism/pressure”). The opposite of impervious, pervious, entered English at around the same time, but it is much less common.

Synonyms

• tight
• impermeable
• thick
• impenetrable

Examples of impervious in a Sentence

He looked at her, impervious to her tears … —Jean Stafford, Children Are Bored on Sunday, (1945) 1953

… the trunk … is encased in so hard a bark, as to be almost impervious to a bullet … —Herman Melville, Omoo, 1847

… Berlin struck me, above all, as impervious to any political reactions whatever … —Stephen Spender, New York Times Magazine, 30 Oct.1977

the material for this coat is supposed to be impervious to rain

the rain forest is impervious to all but the most dedicated explorers

Recent Examples on the Web

Urban heat islands are areas within cities that are significantly warmer than the surrounding areas, and this is primarily due to the replacement of natural surfaces with impervious materials like pavement and buildings. —Stephen Underwood, Hartford Courant, 16 June 2025

First, the team looked at the microbiomes of corals that are impervious to SCTLD to try and harvest probiotics from these disease-resistant species. —Laura Baisas, Popular Science, 5 June 2025

These include the claim that children are virtually impervious to COVID, which has been refuted by the injury and death toll among children. —Michael Hiltzik, Los Angeles Times, 5 June 2025

Alcoholic beverages are virtually impervious to pathogens but can only be consumed in limited quantities. —Ali Bouzari, Bon Appetit Magazine, 28 Mar. 2025

Word History

Etymology

Latin impervius, from in- + pervius pervious

First Known Use

1615, in the meaning defined at sense 1a

Rhymes for impervious

• pervious

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Kids Definition

impervious

adjective

im·​per·​vi·​ous (ˈ)im-ˈpər-vē-əs 

1

: not letting something enter or pass through

a coat impervious to rain

2

: not disturbed or upset

impervious to criticism

imperviousness noun

Medical Definition

impervious

adjective

im·​per·​vi·​ous (ˈ)im-ˈpər-vē-əs 

: not allowing entrance or passage

medication packaged in a container impervious to air and light

imperviousness noun