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”

Related Words

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