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Definition of unreliable

unreliable

/ˌʌnrɪˈlaɪəbəl/
un · re · li · a · ble
Adverb:unreliably
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unreliable Lexical Profile

unreliable Game Scores & Validity

• adjective

1

Not able to be trusted or depended upon to fulfill obligations, keep promises, or act consistently.

Example

"The contractor proved to be so unreliable that we had to hire someone else to finish the renovation."

2

Consistently failing to function properly or produce accurate, predictable results (of a machine, system, or source of information).

Example

"Historians are cautious about citing that chronicle because its dates are notoriously unreliable."

Synonyms
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Antonyms
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• Rhymes for unreliable

• Nearby Words

unrelenting
unrelentingly
unreliability
unreliable
unreliableness
unreliably
unrelieved

Word Origin & Etymology

Formed in the early 19th century by adding the Old English negative prefix 'un-' to 'reliable', which itself derives from the Old French 'relier' (to bind or fasten together), from the Latin 'religare'.

Cite this Entry

Wordmom. (2026). Definition of Unreliable. In Wordmom Dictionary. Retrieved Nov 5, 2026, from https://wordmom.com/dictionary/unreliable
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