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

• ˈtreacherousness, noun
• ˈtreacherously, adverb

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

After a treacherous journey through an undisclosed route over the mountains on foot, followed by multiple stops over the course of 28 days, he eventually made it to safety in Germany.

From Los Angeles Times

He mentioned that last week the Drones Road, one of the main roads leading to Ballycastle, was treacherous following snow and ice.

From BBC

Navigating those subtle shifts in the electorate may be tricky, however, and overcorrecting too far to the right may prove just as treacherous.

From Los Angeles Times

Huge metal containers – broken free from their articulated lorries – rested at unfathomable angles amid a jumble of cars, crumpled furniture and treacherous mud.

From BBC

The pilot of a small plane that crashed on Santa Catalina Island, killing five, was warned not to take off in treacherous conditions after dark.

From Los Angeles Times

Related Words

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