treach·​er·​ous ˈtre-chə-rəs How to pronounce treacherous (audio)
: likely to betray trust : unreliable
a treacherous memory
: providing insecure footing or support
treacherous quicksand
: marked by hidden dangers, hazards, or perils
: characterized by or manifesting treachery : perfidious
treacherously adverb
treacherousness noun
Choose the Right Synonym for treacherous

faithless, false, disloyal, traitorous, treacherous, perfidious mean untrue to what should command one's fidelity or allegiance.

faithless applies to any failure to keep a promise or pledge or any breach of allegiance or loyalty.

faithless allies

false stresses the fact of failing to be true in any manner ranging from fickleness to cold treachery.

betrayed by false friends

disloyal implies a lack of complete faithfulness to a friend, cause, leader, or country.

disloyal to their country

traitorous implies either actual treason or a serious betrayal of trust.

traitorous acts punishable by death

treacherous implies readiness to betray trust or confidence.

a treacherous adviser

perfidious adds to faithless the implication of an incapacity for fidelity or reliability.

a perfidious double-crosser

Examples of treacherous in a Sentence

a treacherous act of betrayal They were not prepared to hike over such treacherous terrain. The snow made their hike all the more treacherous. Discussions about money can lead couples into treacherous territory.
Recent Examples on the Web But lashes that are designed to thrive in these treacherous conditions are even harder to come by. Alyssa Brascia, Peoplemag, 17 May 2024 While Bleecker is celebrating its 10th anniversary, many of its competitors haven’t managed to survive in a business that’s only become more treacherous to navigate. Brent Lang, Variety, 15 May 2024 See all Example Sentences for treacherous 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'treacherous.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

14th century, in the meaning defined at sense 2

Time Traveler
The first known use of treacherous was in the 14th century

Dictionary Entries Near treacherous

Cite this Entry

“Treacherous.” Dictionary, Merriam-Webster, Accessed 24 May. 2024.

Kids Definition


treach·​er·​ous ˈtrech-(ə-)rəs How to pronounce treacherous (audio)
: guilty of treachery
: likely to betray : unreliable
a treacherous memory
: giving a false appearance of safety or solidity
a treacherous stretch of bog
treacherously adverb

More from Merriam-Webster on treacherous

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