unreliable

adjective

un·​re·​li·​able ˌən-ri-ˈlī-ə-bəl 

: not reliable : undependable, untrustworthy

an unreliable friend

an unreliable source of funding

an unreliable car

unreliability

ˌən-ri-ˌlī-ə-ˈbi-lə-tē 

noun

the unreliability of the data

a person with a reputation for unreliability

unreliably

ˌən-ri-ˈlī-ə-blē 

adverb

a method that works unreliably

Examples of unreliable in a Sentence

Recent Examples on the Web

Agents operating on poor data will make confident, autonomous decisions based on unreliable or even hazardous inputs. — Imran Aftab, Forbes.com, 6 Aug. 2026

The bus is both faraway and unreliable, and the bike ride is harrowing. — Nina Moskowitz, Bon Appetit Magazine, 6 Aug. 2026

Realbotix says those guardrails are designed to block inappropriate responses and reduce unreliable outputs. — Jesse Watson, FOXNews.com, 3 Aug. 2026

Chemical cues floating in the air in the natural environment are often sparse and unreliable. — Jacek Krywko, ArsTechnica, 1 Aug. 2026

Word History

First Known Use

1810, in the meaning defined above

Rhymes for unreliable

• liable
• pliable
• triable
• viable
• classifiable
• justifiable
• modifiable
• notifiable
• satisfiable
• specifiable
• undeniable
• verifiable