unacceptable

The word “unacceptable” means not good enough to be allowed, approved of, or tolerated. In plain terms, so far below standard, or so inappropriate, that it cannot be permitted or excused.

“Unacceptable” is pronounced uhn-ak-SEHP-tuh-bl (/ˌʌn.ækˈsɛp.tə.bl̩/ in IPA).

Here is “unacceptable” used in a sentence: “The manager said the delay in shipping was unacceptable.”

Words with a similar meaning to “unacceptable” include inacceptable and out of bounds.

The opposite of “unacceptable” — its antonyms — is acceptable.

“Unacceptable” is an adjective.

The word “unacceptable” comes from Middle English. From Middle English unacceptabylle, built from un- plus acceptable.

“Unacceptable” is a fairly common word in modern English, usually learned at around the B2 level.

Both mean not able to be accepted, but "unacceptable" is the standard and far more common form in modern English. "Inacceptable" is rare and can sound old-fashioned, so "unacceptable" is almost always the better choice.

"Unacceptable" means not good enough to be allowed or tolerated and is strongly disapproving, while "inappropriate" means not suitable for a particular situation. Behaviour can be inappropriate without being fully unacceptable, but "unacceptable" implies it cannot be permitted at all.

Yes, "unacceptable" is a strong, firm term signalling that something will not be tolerated or approved, and it is common in complaints and official statements. Softer alternatives include "not ideal," "disappointing," or "unsatisfactory" when a milder tone is wanted.

"Unacceptable" often precedes behaviour, risk, level, conduct, and delay, as in "unacceptable behaviour" and "unacceptable risk." It appears frequently in formal complaints, workplace policies, and official warnings.