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Origin of unreliable

First recorded in 1830–40; un-1 + reliable
Related formsun·re·li·a·bil·i·ty, un·re·li·a·ble·ness, nounun·re·li·a·bly, adverb

Synonyms for unreliable

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Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

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British Dictionary definitions for unreliable


  1. not reliable; untrustworthyan 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

Word Origin and History for unreliable

1840, from un- (1) "not" + reliable. First recorded in De Quincey, who said it was coined by Coleridge.

Online Etymology Dictionary, © 2010 Douglas Harper