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treacherous

[ trech-er-uhs ]
/ ˈtrɛtʃ ər əs /
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See synonyms for: treacherous / treacherously / treacherousness on Thesaurus.com

adjective
characterized by faithlessness or readiness to betray trust; traitorous.
deceptive, untrustworthy, or unreliable.
unstable or insecure, as footing.
dangerous; hazardous: a treacherous climb.
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Origin of treacherous

First recorded in 1300–50; Middle English trecherous, from Anglo-French, equivalent to trecher “deceiver” (trech(ier) “to deceive” + -er -er2) + -ous -ous; compare French tricheur “trickster”

OTHER WORDS FROM treacherous

treach·er·ous·ly, adverbtreach·er·ous·ness, nounun·treach·er·ous, adjectiveun·treach·er·ous·ness, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022

How to use treacherous in a sentence

British Dictionary definitions for treacherous

treacherous
/ (ˈtrɛtʃərəs) /

adjective
betraying or likely to betray faith or confidence
unstable, unreliable, or dangeroustreacherous weather; treacherous ground

Derived forms of treacherous

treacherously, adverbtreacherousness, noun
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
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