English Reference
adjective · noun

unacceptable

adj. · n.
US /ˌənækˈsɛptəbəɫ/ UK /ʌnɐksˈɛptəbəl/ un·ac·cept·able

  1. 01 B2 Upper Intermediate

    adj.not good enough to be allowed or accepted by others.

    adj.failing to meet a required standard or social expectation; deemed intolerable or unsatisfactory.

    Simple

    The long delays at the airport were completely unacceptable to the passengers.

    In context

    The committee found the proposed safety measures to be wholly unacceptable, citing numerous gaps in the emergency evacuation protocols.

  2. 02 C1 Advanced AcademicTechnical Science

    adj.describing a word or sentence that does not follow the rules of a language.

    adj.describing a linguistic form that does not conform to the rules of a specific grammar or the norms of a speech community.

    Simple

    In English, saying 'he go' is considered unacceptable in formal writing.

    In context

    The generative model rejected the string as unacceptable because it violated the core principles of phrase structure within that specific dialect.

    Usage

    In linguistics, this is often marked with an asterisk (*) before the sentence.

    ungrammaticalill formed
    grammaticalwell formed
  3. 03 C2 Proficiency Formal

    n.a person or thing that is not accepted by a group.

    n.an entity, person, or proposal that has been rejected or deemed unsuitable for inclusion.

    Simple

    The social club was known for its harsh treatment of unacceptables.

    In context

    The archive was divided into two sections: those documents deemed worthy of preservation and the unacceptables destined for the shredder.

Usage unacceptable public

I think the cruelty that I've experienced and the positioning of me as this kind of liar and fantasist is totally unacceptable," he told the Times newspaper , external earlier this month.

BBC News· 15 Aug 2026

A public inquiry found authorities covered up the scandal and exposed victims to unacceptable risks.

BBC News· 11 Aug 2026

From Middle English unacceptabylle, equivalent to un- + acceptable.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin Middle English unacceptabylle
Level B2 · Upper Intermediate
Frequency Frequent
Updated