ENGLISH
REFERENCE

diagnostic

adj. · n.
US //ˌdaɪəɡˈnɑstɪk// UK //dˌaɪəɡnˈɒstɪk// di·ag·nos·tic
  1. 1 medical/technical identification (adj.)
    B2 Upper Intermediate Technical Medicine

    used to help identify a disease or a technical problem.

    relating to or used in the identification of a medical condition or a technical malfunction.

    Example

    The doctor ordered a diagnostic test to see why the patient was feeling dizzy.

    Example

    The hospital invested in advanced diagnostic imaging equipment to improve the accuracy of early-stage cancer detection.

    Usage

    Often modifies nouns like 'test', 'tool', or 'procedure'.
  2. 2 educational assessment (adj.)
    B2 Upper Intermediate Academic Education

    a test given at the start of a course to see what you already know.

    designed to assess a learner's strengths, weaknesses, and prior knowledge before instruction begins.

    Example

    We took a diagnostic quiz on the first day of the Spanish class.

    Example

    The diagnostic assessment revealed that while the students had strong vocabulary skills, they struggled significantly with complex grammatical structures.
    • pre assessment
  3. 3 a tool or test (n.)
    C1 Advanced Technical Computing

    a specific test or program used to find a fault or problem.

    a procedure, program, or tool used to identify the cause of a problem or the nature of a condition.

    Example

    The mechanic ran a diagnostic on the car's engine to find the leak.

    Example

    After the system crash, the IT department ran a full suite of diagnostics to determine if the failure was hardware-related or a software bug.

    Usage

    Frequently used in the plural form 'diagnostics' when referring to computer routines.
Origin

From Ancient Greek διαγνωστικός (diagnōstikós), adjective from διαγιγνώσκω (diagignṓskō, “to distinguish, diagnose”).

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

Related words

Last updated June 20, 2026