treacherous

[ trech-er-uhs ]

adjective

1. characterized by faithlessness or readiness to betray trust; traitorous.

   Synonyms: treasonous, faithless, unfaithful

   Antonyms: loyal

2. deceptive, untrustworthy, or unreliable.

   Synonyms: deceitful

   Antonyms: reliable

3. unstable or insecure, as footing.
4. dangerous; hazardous:

   a treacherous climb.

treacherous

/ ˈtrɛtʃərəs /

adjective

1. betraying or likely to betray faith or confidence
2. unstable, unreliable, or dangerous

   treacherous weather

   treacherous ground

Derived Forms

• ˈtreacherously, adverb
• ˈtreacherousness, noun

Other Words From

• treach·er·ous·ly adverb
• treach·er·ous·ness noun
• un·treach·er·ous adjective
• un·treach·er·ous·ness noun

Word History and Origins

Origin of treacherous¹

First recorded in 1300–50; Middle English trecherous, from Anglo-French, equivalent to trecher “deceiver” ( trech(ier) “to deceive” + -er -er ² ) + -ous -ous; compare French tricheur “trickster”

Example Sentences

He spent almost 200 miles dodging massive hornets and fire ants, hopping from downed tree to downed tree, and crossing treacherous rivers with about 100 other racers and nothing but the food he could carry and an occasional water refill.

From Popular-Science

Pernigotti said that only those who regularly climb in the Alps can appreciate how warmer weather has made the mountains more treacherous.

From Outside Online

Observations from Earth suggested Bennu should be smooth and sandy, but when OSIRIS-REx arrived, it found a treacherous, rocky landscape.

From Science News

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.

From 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.

From Voice of San Diego

True, we travel this treacherous road at our own risk, but … *** Bob Weir: “If you want something for nothing, go jerk off.”

From The Daily Beast

Big scary Transformer-like robots with heads ablaze that frighten the kids back across the treacherous desert?

From The Daily Beast

While the journey north was always treacherous and costly, in the hands of the cartels it has become deadlier than ever.

From The Daily Beast

Treacherous thatched-roof-haired drag-queen Linda Tripp, with those dress-for-success shoulder pads?

From The Daily Beast

Soviet forces slowed Nazi advances, however, by laying vast and treacherous minefields.

From The Daily Beast

This treacherous sort of calm, we thought, might forbode a storm, and we did not allow it to lull us into security.

From Project Gutenberg

The profound and treacherous night with its silence and semblance of peace settled upon the camp.

From Project Gutenberg

In a sudden, blind choler, she swept round, plucked the dagger from Tressan's belt and flung herself upon the treacherous captain.

From Project Gutenberg

Intellectually she is quite sound, but has a treacherous memory, and is very nervous.

From Project Gutenberg

A faithless woman, if known to be such by the person concerned, is but faithless; if she is believed faithful, she is treacherous.

From Project Gutenberg

Related Words

• difficult
• hazardous
• icy
• ominous
• perilous
• precarious
• risky
• slippery
• ticklish
• tricky
• unreliable
• unsafe
• unstable