characterized by faithlessness or readiness to betray trust; traitorous.
deceptive, untrustworthy, or unreliable.
unstable or insecure, as footing.
dangerous; hazardous: a treacherous climb.
Origin of treacherous
1300–50; Middle English trecherous<Anglo-French, equivalent to trecher deceiver (trech(ier) to deceive + -er-er2) + -ous-ous. Cf. French tricheur trickster
The incident highlighted the treacherous news landscape where both reporters and policymakers now tread, one in which even protecting children can be weaponized by extremists.
He’s Fighting QAnon With Sunlight|Nick Fouriezos|September 6, 2020|Ozy
To Filner, the treacherous San Diego business insiders, developers and Republicans had rigged the city’s political system to send resources to their pet projects and away from neighborhoods.
Politics Report: Bry vs. Transit|Andrew Keatts and Scott Lewis|August 29, 2020|Voice of San Diego
Big scary Transformer-like robots with heads ablaze that frighten the kids back across the treacherous desert?
The So-Called Immigration Border Crisis Is Neither|Sally Kohn|July 10, 2014|DAILY BEAST
Treacherous thatched-roof-haired drag-queen Linda Tripp, with those dress-for-success shoulder pads?
How Monica Lewinsky Changed the Media|Tina Brown|May 9, 2014|DAILY BEAST
Unsurprisingly, treacherous murmurings are starting to be heard again of the crown skipping a generation.
How 2012 Turned Into a Very Bad Year For Prince Charles|Tom Sykes|November 26, 2012|DAILY BEAST
The place where the Constitution meets religion and race remains a treacherous cultural battleground.
The Constitution and the Candidates: Race, Religion, Romney, and Ryan|Akhil Reed Amar|August 19, 2012|DAILY BEAST
To resist such a project is a treacherous endeavor more akin to a marathon than a sprint.
Prisoners in Parallel|Ismail Khalidi|June 7, 2012|DAILY BEAST
His stabs are delivered like those of a bravo, who hides his face as he deals his treacherous blow.
Flowers of Freethought|George W. Foote
It is a treacherous, dishonest weapon, to be sure; but have I been frank and honest?
Within an Inch of His Life|Emile Gaboriau
The barge in which Agrippina was thus invited to embark, was the treacherous trap that Anicetus had contrived for her destruction.
Nero|Jacob Abbott
Another thing, little old churches look easy, but they're apt to be treacherous.
Careers of Danger and Daring|Cleveland Moffett
The treacherous enemy having broken the armistice, the burning of the Palace-castle of Chapultepec followed soon arter.
The Guerilla Chief|Mayne Reid
British Dictionary definitions for treacherous
treacherous
/ (ˈtrɛtʃərəs) /
adjective
betraying or likely to betray faith or confidence
unstable, unreliable, or dangeroustreacherous weather; treacherous ground