English Reference
adjective · noun

diagnostic

adj. · n.
US /ˌdaɪəɡˈnɑstɪk/ UK /dˌaɪəɡnˈɒstɪk/ di·ag·nos·tic UK spelling diagnostic's, diagnostic's

  1. 01 B2 Upper Intermediate Technical Medicine

    adj.used to help identify a disease or a technical problem.

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

    Simple

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

    In context

    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. 02 B2 Upper Intermediate Academic Education

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

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

    Simple

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

    In context

    The diagnostic assessment revealed that while the students had strong vocabulary skills, they struggled significantly with complex grammatical structures.

    pre assessment
  3. 03 C1 Advanced Technical Computing

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

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

    Simple

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

    In context

    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.

Usage diagnostic capacity

If you do, then this, like other diagnostic tests in the public system, will be free.

The Local· 13 Aug 2026

Improving accuracy is important because the average human error rates involving diagnostic images are estimated to range from 3 to 5 percent, which translates to about 40 million errors worldwide each year .

Smithsonian Magazine· 29 Jul 2026

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

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

This entry
Origin Ancient Greek διαγνωστικός
Level B2 · Upper Intermediate
Frequency Frequent
Updated