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unacceptable

adj. · n.
US //ˌənækˈsɛptəbəɫ// UK //ʌnɐksˈɛptəbəl// un·ac·cept·able
  1. 1 not good enough (adj.)
    B2 Upper Intermediate

    not good enough to be allowed or accepted by others.

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

    Example

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

    Example

    The committee found the proposed safety measures to be wholly unacceptable, citing numerous gaps in the emergency evacuation protocols.
  2. 2 linguistically incorrect (adj.)
    C1 Advanced Academic Technical Science

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

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

    Example

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

    Example

    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.
    • ungrammatical
    • ill formed
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  1. 3 something rejected (n.)
    C2 Proficiency Formal

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

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

    Example

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

    Example

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

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

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