treach·​er·​ous | \ˈtre-chə-rəs, ˈtrech-rəs\

Definition of treacherous 

1a : likely to betray trust : unreliable a treacherous memory

b : providing insecure footing or support treacherous quicksand

c : marked by hidden dangers, hazards, or perils

2 : characterized by or manifesting treachery : perfidious

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Other Words from treacherous

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.
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Recent Examples on the Web

Ekapol helped keep the boys breathing and emotionally balanced during the crisis, and also readied them for their hours-long treacherous escape guided by expert cave divers. Kristin Clark Taylor, Washington Post, "Thai soccer coach meditated with boys to calm them in the cave. We can all learn from them.," 11 July 2018 The lush forests of northern Thailand are home to hundreds of caves that attract visitors, but Tham Luang Nang Non is deeper and more dangerous than most, and especially treacherous during the rainy season. Times Staff,, "A curious soccer team, a flooded Thai cave and a perilous trek to safety," 8 July 2018 Creating a map of treacherous and friendly locations Instead of guessing which ones are helpful, the researchers built a simplified model of the magnetic fields associated with the plasma. Chris Lee, Ars Technica, "A third dimension helps Tokamak fusion reactor avoid wall-destroying instability," 13 Sep. 2018 Morrison explained his deep belief in the righteousness of crushing the people-smuggling trade and preserving the safety of people who board rickety boats to take the long and treacherous voyage to Australia. Rod Mcguirk, Fox News, "Next Australian prime minister well placed to heal party," 23 Aug. 2018 Today, with Mexico’s economy and birth rate both stable, nearly half come from Honduras, Guatemala and El Salvador—weak states wracked by gang violence—enduring a costly and treacherous journey north. The Economist, "America’s immigration system is broken," 28 June 2018 The tournament rotates among sites of disparate design — some old, some new, but all configured with impossible rough and treacherous greens designed to crush a golfer’s spirit. Marcus Hayes,, "Curtis Strange embraces the idea of Brooks Koepka joining his U.S. Open club," 18 June 2018 The fire brigade changed the guidance at 2:47 a.m. By that time, the building's only stairwell was smoke-filled and treacherous. Jill Lawless,, "A year on, Grenfell Tower 'atrocity' haunts Britain," 14 June 2018 The journey New Orleans had to go through to reach this stage was a long and treacherous one, but the path to sustaining that success will be twice as difficult. William Guillory,, "Pelicans' playoff success leads to added recognition, but what happens next could be telling," 26 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'treacherous.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of treacherous

14th century, in the meaning defined at sense 2

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treacle mold

Statistics for treacherous

Last Updated

12 Dec 2018

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Time Traveler for treacherous

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

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English Language Learners Definition of treacherous

: not able to be trusted : showing that someone cannot be trusted

: very dangerous and difficult to deal with


treach·​er·​ous | \ˈtre-chə-rəs \

Kids Definition of treacherous

1 : not safe because of hidden dangers This was a treacherous road at night …— John Reynolds Gardiner, Stone Fox

2 : not trustworthy : guilty of betrayal or likely to betray a treacherous enemy

Other Words from treacherous

treacherously adverb

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a nest or breeding place

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