ENGLISH
REFERENCE

unauthorized

adj.
US //əˈnɔθɝˌaɪzd// unau·tho·rized
  1. 1 without permission (adj.)
    B2 Upper Intermediate Formal

    not having official permission to happen or to be in a place.

    done or occurring without official authorization, sanction, or legal permission.

    Example

    The security guard stopped the man for making an unauthorized entry into the building.

    Example

    The IT department detected several unauthorized attempts to access the company's private database from an external server.

    Usage

    Usually placed before the noun it modifies.

    Teacher's tip

    This is a common term in legal, security, and digital contexts; it sounds much more formal than 'not allowed'.
Origin

From un- + authorized.

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