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

This was related to separate charges involving impermissible contact to register academy players between 2019 and 2022.

From BBC • Mar. 16, 2026

Multiple courts noted the government’s repeated assurances throughout this litigation, and several opinions flagged that reversing course would be impermissible.

From The Wall Street Journal • Feb. 22, 2026

Judges doesn’t discuss every possible impermissible activity that exists under the sun.

From Slate • Dec. 11, 2025

Circuit Court of Appeals held in 2022 that “the prosecution of foreign nationals traveling on such a vessel for a violation of U.S. law is impermissible under the Felonies Clause of the Constitution.”

From The Wall Street Journal • Dec. 8, 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