What does impermissible mean?
Impermissible is a formal adjective meaning not allowed, permitted, or authorized. It is used when a rule, law, agreement, policy, or other authority expressly prohibits an action or condition. The term often appears in legal and regulatory writing, as well as in formal contracts and institutional guidelines. For example, a contract may describe unauthorized disclosure of information as impermissible conduct. Although impermissible often overlaps with forbidden and prohibited, it can also suggest that a boundary has been formally defined rather than merely discouraged. A related distinction is that illegal specifically concerns violations of law, while impermissible can refer to any clearly stated prohibition. The word is related to the root meaning “permit,” and its negative prefix “im-” expresses the opposite of what is permissible.
adjectiveNot allowed or permitted; forbidden. It describes conduct, actions, or uses that are expressly prohibited by a rule, law, agreement, or authority.
- Not allowed or permitted; forbidden.
"The committee ruled that using the company’s confidential data for personal purposes was impermissible."
"It would be impermissible for spectators to enter the restricted area without authorization."
"The agreement makes any attempt to alter the records impermissible."
Impermissible is the word for crossing a line that has been clearly drawn, whether by law, policy, etiquette, or an agreement.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does impermissible come from?
Impermissible derives from the Latin word permissibilis, meaning “that may be permitted,” formed from the root of permittere, “to allow.” The English cognates permissible, permissive, and permission share this Latin foundation. By adding the negative prefix im- and changing the inflectional ending, impermissible came to mean “not allowable” or “forbidden.”
Related word forms
How impermissible is actually used
The word is formal and commonly used in legal, regulatory, institutional, and contractual contexts. It is often more emphatic than simply saying that something is not allowed.
Easily confused with impermissible
Illegal refers specifically to conduct prohibited by law, whereas impermissible more broadly means forbidden by any applicable rule, agreement, or authority.
Unacceptable describes conduct judged undesirable or objectionable, while impermissible indicates that it is formally or expressly not allowed.