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

Ministers say the move, announced alongside a government-commissioned review earlier this year, will reduce the risk that impermissible donations from foreign nationals will "slip through the net".

From BBC • Jun. 4, 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

Again, it’s pretty obvious to me that this was an impermissible attendance, under the canons.

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

Supreme Court announced its decision: Life imprisonment without parole sentences imposed on children convicted of non-homicide crimes is cruel and unusual punishment and constitutionally impermissible.

From "Just Mercy" by Bryan Stevenson