# reliability

/ɹiˌɫaɪəˈbɪɫəti/ (US) · /ɹɪlˌaɪəbˈɪlɪti/ (UK)

Source: https://englishreference.com/word/reliability
Updated: 2026-06-20

## Senses

### 1. trustworthiness

noun · CEFR B2

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

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

- The company is famous for the reliability of its cars, which rarely break down.
- The manager questioned the reliability of the witness's testimony after several inconsistencies were discovered during the cross-examination.

Usage: Uncountable in general usage.

### 2. consistency of measurement

noun · CEFR C1 · Academic · Technical

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

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

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

noun · CEFR C1 · Technical

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

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

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

## Examples

- The car is famous for its mechanical reliability.
- When choosing a new supplier, the company prioritizes reliability over low costs to avoid production delays.
- Engineers must conduct rigorous stress tests to ensure the long-term reliability of the bridge's structural components under extreme weather conditions.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.