Word
unreliable
Phoneticsun·re·li·able
US/ˌənɹiˈɫaɪəbəɫ/
UK/ˌʌnɹɪlˈaɪəbəl/
Definitions
01not trustworthy or consistent
B1 · Intermediate
adj. not able to be trusted or depended on to do something well or to be true.
adj. lacking reliability; prone to failure, inconsistency, or inaccuracy.
“The bus service is very unreliable, so I usually walk to work instead.”
“The witness was deemed unreliable by the prosecution after several major inconsistencies were discovered in her initial statement.”
Synonyms
Antonyms
02a person or thing that fails
C2 · Proficiency Countable noun Formal
n. a person or thing that you cannot depend on.
n. an entity, whether a person or a mechanical system, that consistently fails to perform as expected.
“Among all the new machines we bought, this one has been a total unreliable.”
“The report identified the aging generator as a chronic unreliable, recommending its immediate replacement to avoid further power outages.”
Usage
This noun use is much rarer than the adjective form and typically appears in formal or technical reports.
Etymology
From un- + reliable.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
- Exam level
- CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.B1 PreliminaryIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.4.0–5.0TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 3.0–3.544–71TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.550–784
- Frequency
- Frequent
- Level
- B1 · Intermediate
- Updated
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