English Reference
adjective

unofficial

adj.
US /ˌənəˈfɪʃəɫ/ UK /ʌnəfˈɪʃəl/ un·of·fi·cial

  1. 01 B2 Upper Intermediate

    not confirmed or approved by an organization, government, or person in charge.

    lacking formal sanction, confirmation, or authorization from a governing body or official source.

    Simple

    The unofficial results of the election were shared on social media before the final count.

    In context

    Although the deal was common knowledge among the staff, it remained unofficial until the board of directors signed the final contract.

  2. 02 B2 Upper Intermediate

    doing something without having the legal right or power to do it.

    acting without the requisite legal or institutional authority; often used to describe roles or actions taken outside of formal structures.

    Simple

    He acted as an unofficial advisor to the president for many years.

    In context

    The committee was criticized for its unofficial investigation, which many felt overstepped its legal boundaries and lacked transparency.

  3. 03 C2 Proficiency Technical Medicine

    describes a medicine or chemical that is not listed in an official medical book.

    referring to a medicinal substance or preparation not listed in a national or international pharmacopeia.

    Simple

    The doctor warned that the unofficial remedy had not been tested for safety.

    In context

    The laboratory identified several unofficial compounds in the herbal supplement that were not disclosed on the product label.

    Usage

    Usually placed before the noun it modifies.

    non pharmacopeial

They also embraced a friend of the family, James, as an unofficial son, and James’s children, Dylan and Maisie, came to view them as grandparents.

The Guardian· 10 Aug 2026

One of his poems is about a child in some unnamed village near the frontline, who becomes the unofficial mascot of the soldiers posted there.

The Guardian· 10 Aug 2026

From un- + official.

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

This entry
Level B2 · Upper Intermediate
Frequency Frequent
Updated