English Reference
noun

reliability

n.
US /ɹiˌɫaɪəˈbɪɫəti/ UK /ɹɪlˌaɪəbˈɪlɪti/ re·li·a·bil·i·ty UK spelling reliabilities

  1. 01 B2 Upper Intermediate

    the quality of being able to be trusted or relied on.

    the quality of being dependable, consistent, or trustworthy in character or performance.

    Simple

    The company is famous for the reliability of its cars, which rarely break down.

    In context

    The manager questioned the reliability of the witness's testimony after several inconsistencies were discovered during the cross-examination.

    Usage

    Uncountable in general usage.

    dependabilitytrustworthinessconsistency
    unreliabilityfickleness
  2. 02 C1 Advanced AcademicTechnical Science

    the ability of a test or tool to give the same result every time you use it.

    the degree to which an assessment tool produces stable and consistent results over repeated trials.

    Simple

    The researchers checked the reliability of the survey by giving it to the same group twice.

    In context

    High reliability does not necessarily imply validity; a scale might consistently overstate weight by five kilograms, making it reliable but inaccurate.

    Usage

    Often contrasted with 'validity' in research contexts.

  3. 03 C1 Advanced Technical Science

    how long a machine or system works before it fails or breaks.

    the probability that a system or component will perform its required function under stated conditions for a specified period.

    Simple

    Engineers are working to improve the reliability of the new power grid.

    In context

    The aerospace industry demands extreme levels of reliability, as even a minor component failure can have catastrophic consequences during flight.

    Usage

    Commonly used in engineering and systems design.

Usage ensure reliability · establish reliability · increase reliability

Such systems could reduce communication and energy constraints at the lunar poles, but long-duration reliability, navigation in shadowed terrain, dust tolerance and interoperability remain unresolved.

Phys.org· 15 Aug 2026

Texas’ policies have prioritized gas and battery plant construction to help bolster the power grid’s reliability at times of high demand.

Ars Technica· 15 Aug 2026

From reliable + -ity.

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

This entry
Level C1 · Advanced
Frequency Frequent
Updated