What does reliability mean?
Reliability describes the quality of something that can be trusted to work, remain consistent, or meet expectations. People speak of the reliability of a person when they mean dependability, and of the reliability of a product, service, system, or piece of information when they mean that it performs consistently and is unlikely to fail or produce error. The word is especially common in technical, scientific, industrial, and business contexts, where reliability is often evaluated through testing and measurable performance standards. It can also carry a broader social sense, suggesting steadiness and trustworthiness over time. Reliability is a useful word because it identifies a quality that matters in almost every setting: from transport and software to medicine, education, and personal relationships. A reliable thing may not be exciting or innovative, but people can consistently depend on it, making reliability a form of practical strength and confidence.
nounThe quality of being dependable, trustworthy, or consistent, especially the likelihood that a person, system, process, or result will perform as expected.
- The quality of being dependable, trustworthy, or consistent over time.
- The extent to which a system, process, measurement, or result performs consistently and remains free from significant error.
"The company is known for the reliability of its products and its commitment to customer service."
"The train's reliability has improved since the schedule was redesigned."
"Reliability testing revealed that the device continued to function under extreme temperature conditions."
The plural is grammatically correct but uncommon in ordinary use; discussions often compare the reliability of different items instead.
"The study compares the reliabilities of several navigation systems."
Reliability grew from the idea of binding: its Latin ancestor meant “to bind back,” so a reliable thing is one you can count on.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does reliability come from?
Reliability was formed in English from reliable plus the suffix -ity, meaning state, condition, or quality. Reliable comes from rely, which ultimately traces to Old French relyer and Latin religare, “to bind back,” built from re- and ligare, “to bind.” The development therefore moves from the idea of binding or fastening to that of depending on someone or something with confidence.
How reliability is actually used
Reliability is common in formal and technical writing as well as everyday speech. In engineering and statistics, it can specifically refer to the probability that a component or system will perform its intended function under stated conditions.
Easily confused with reliability
Reliability is the quality of being dependable, whereas reliance is the act or condition of depending on someone or something.