Dictionary.com
Thesaurus.com
Synonyms

unreliable

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

adjective

  1. not reliable; not to be relied or depended on.

    Synonyms:
    untrustworthy, irresponsible, undependable

unreliable British  
/ ˌʌnrɪˈlaɪəbəl /

adjective

  1. not reliable; untrustworthy

    an unreliable witness

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

Etymology

Origin of unreliable

First recorded in 1830–40; un- 1 + reliable

Explanation

Someone unreliable can't be trusted to do something. Things can be unreliable too, like a bike with a wobbly wheel. The word "rely" is a clue to what unreliable means. When you can rely on something, you can count in it — it's reliable. On the other hand, you'd better not count on an unreliable person. People can be unreliable because they're dishonest, always late, bad at their job, or just inconsistent. Things can be unreliable because they're broken or old. A train schedule can be unreliable if the trains are never on time. Unfortunately, there's a lot of stuff in life that's unreliable, so be careful.

Keep Reading on Vocabulary.com

Vocabulary lists containing unreliable

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.

The companies have been added to Beijing's List of Unreliable Entities, and are prohibited from engaging in import and export activities related to China, the ministry said.

From BBC • May 19, 2024

Not at all the imposter she labels herself in her new memoir "Unreliable Narrator."

From Salon • Oct. 1, 2023

Unreliable narrators continue to write women out of history, and it’s one of my goals to write them back in.

From Los Angeles Times • Mar. 31, 2023

Unreliable plans are platforms to talk about expectations, respect, limits, discretion, boundaries — when, where, how, and why to set them.

From Washington Post • Aug. 27, 2021

About nine o'clock the Unreliable came and asked Gov.

From The Wit and Humor of America, Volume X (of X) by Wilder, Marshall Pinckney