English Reference
adjective · noun

classified

adj. · n.
US /ˈkɫæsəˌfaɪd/ UK /klˈæsɪfˌaɪd/ clas·si·fied

  1. 01 B2 Upper Intermediate Formal

    adj.official information that is secret and only certain people are allowed to see.

    adj.formally designated by a government or organization as sensitive, requiring specific security clearance for access.

    Simple

    The general refused to answer questions about the classified documents.

    In context

    The whistleblower was charged with leaking classified intelligence that the government claimed would jeopardize national security if made public.

    Usage

    Often used with nouns like 'information', 'documents', or 'files'.

  2. 02 B2 Upper Intermediate Academic

    adj.arranged or organized into different groups or classes.

    adj.arranged into specific categories or classes based on shared characteristics.

    Simple

    The library has books classified by subject so they are easy to find.

    In context

    The biological specimens were classified according to their genetic markers rather than their physical appearance.

    Usage

    Often followed by the preposition 'by' or 'as'.

    randomunsorted
  3. 03 B2 Upper Intermediate Informal

    n.small advertisements in a newspaper or website, usually organized by what is being sold.

    n.small advertisements in a periodical or digital platform, typically grouped by category such as jobs, housing, or services.

    Simple

    I looked through the classifieds to see if anyone was selling a used bike.

    In context

    Before the rise of dedicated online marketplaces, local newspapers relied heavily on the revenue generated by the classifieds section.

    Usage

    Almost always used in the plural form 'classifieds'.

    adssmall ads

Men made up more than half of cases in every generation except the oldest classified generation (Silent, born 1928-45), which included only one case, involving a woman.

ScienceDaily· 15 Aug 2026

Meanwhile in North America,  fires are raging in parts of the western United States, while Canada had 591 active fires as of Monday , including 43 classified as out of control.

UN News· 11 Aug 2026

Etymology 1

From classify + -ed.

Etymology 2

From classified advertisement, by shortening.

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

This entry
Level B2 · Upper Intermediate
Frequency Common
Updated