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

Other Word Forms

• treacherously adverb
• treacherousness noun
• untreacherous adjective
• untreacherousness 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

Having survived the even more treacherous descent, Kirsty is thankful to have made it home unscathed.

From BBC

Libya is a major launching pad for migrants who make the treacherous journey across the Mediterranean, hoping to reach the Italian island of Lampedusa.

From BBC

According to police, often the sites targeted are remote, treacherous even, and reminiscent of an Indiana Jones expedition - minus the booby traps.

From BBC

She finds her most treacherous battleground to be none other than luxury grocer Erewhon.

From Los Angeles Times

Following their spiritual leader, the Dalai Lama, they crossed treacherous Himalayan passes and reached India, where they were accepted as refugees on humanitarian grounds and because of shared religious and cultural ties.

From BBC

Related Words

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