unreliable

[uhn-ri-lahy-uh-buhl] / ˌʌn rɪˈlaɪ ə bəl /

ADJECTIVE

not trustworthy, not true

Synonyms

STRONGEST

capricious deceptive dubious false fickle inaccurate irresponsible treacherous tricky uncertain unsound unstable untrustworthy

STRONG

undependable

WEAK

deceitful delusive disreputable erroneous fake fallible fly-by-night furtive hallucinatory hollow implausible inconstant makeshift meretricious mistaken pretended pseudo questionable sham shifty specious unconvincing underhand underhanded unfaithful unsure untrue vacillating wavering weak

Antonyms

STRONGEST

accurate certain clear constant correct definite dependable faithful forthright frank honest reliable right stable steady strong sure true trustworthy truthful

WEAK

responsible

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Polling in mayoral races is typically pretty unreliable.

From Los Angeles Times • Jun. 1, 2026

"Sometimes people pick trains so they have the option of working while they're travelling," she says, adding that operators shouldn't advertise their wi-fi as a benefit of rail travel if it is unreliable.

From BBC • May 30, 2026

Based solely upon a single 1994 interview claiming a precise 50-year memory, such a tale can mislead writers who fail to appreciate how unreliable human memory can be.

From The Wall Street Journal • May 3, 2026

“This letter shows that even utilities like CenterPoint admit that there is no grid emergency and that coal plants are too unreliable, expensive, and polluting to continue operating,” said Ben Inskeep, the coalition’s program director.

From Barron's • Apr. 20, 2026

“It isn’t difficult. If you were lying then, why should a court believe you now? There are no new facts, and you’re an unreliable witness.”

From "Atonement" by Ian McEwan

Vocabulary lists containing unreliable

STAAR English I: Elements of Literature

Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!

STAAR English II: Elements of Literature 1

Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!

Point of View

Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!