impermissible

American  

[im-per-mis-uh-buhl] / ˌɪm pərˈmɪs ə bəl /

adjective

1. not permissible or allowable; unallowable.

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impermissible British  

/ ˌɪmpəˈmɪsɪbəl /

adjective

1. not permissible; not allowed

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Other Word Forms

• impermissibility noun
• impermissibly adverb

Etymology

Origin of impermissible

First recorded in 1855–60; im- ² + permissible

Explanation

Something impermissible isn't allowed. It's impermissible in every part of the U.S. to drive 100 miles an hour on the highway. Things that are permissible are legal, authorized, or welcome — you are permitted to do them. The opposite of permissible is impermissible, which adds the "opposite" prefix im- to permissible, from the Latin permittere, "let, allow, grant, or permit." It's impermissible to bully other kids at school, or against the rules, and it's impermissible to steal a car, or against the law.

Example Sentences

District Court ruled that conditioning minors’ social media participation on parental consent is “an impermissible curtailment of their First Amendment rights.”

From The Wall Street Journal • Mar. 27, 2026

Chamber of Commerce, said swift “refunds of the impermissible tariffs” would help more than 200,000 small-business importers.

From The Wall Street Journal • Feb. 22, 2026

Only the second category is impermissible for power-sector standards.

From Slate • Feb. 20, 2026

But “its public support depends on confidence that the sensitive location data it generates will never be repurposed for impermissible civil immigration enforcement.”

From Los Angeles Times • Oct. 25, 2025

He was given a mandatory death-in-prison sentence after his jury was illegally told that he had to prove his innocence beyond a reasonable doubt and the State introduced impermissible evidence.

From "Just Mercy" by Bryan Stevenson