adjective treach·er·ous \ ˈtre-chə-rəs , ˈtrech-rəs \
|Updated on: 8 Aug 2018

Definition of treacherous

1 a : likely to betray trust : unreliable
  • a treacherous memory
b : providing insecure footing or support
  • treacherous quicksand
c : marked by hidden dangers, hazards, or perils
2 : characterized by or manifesting treachery : perfidious





Examples of treacherous in a Sentence

  1. a treacherous act of betrayal

  2. They were not prepared to hike over such treacherous terrain.

  3. The snow made their hike all the more treacherous.

  4. Discussions about money can lead couples into treacherous territory.

Recent Examples of treacherous from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'treacherous.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of treacherous

14th century

in the meaning defined at sense 2

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Synonym Discussion of treacherous

faithless, false, disloyal, traitorous, treacherous, perfidious mean untrue to what should command one's fidelity or allegiance. faithless applies to any failure to keep a promise or pledge or any breach of allegiance or loyalty.
    • faithless allies
false stresses the fact of failing to be true in any manner ranging from fickleness to cold treachery.
    • betrayed by false friends
disloyal implies a lack of complete faithfulness to a friend, cause, leader, or country.
    • disloyal to their country
traitorous implies either actual treason or a serious betrayal of trust.
    • traitorous acts punishable by death
treacherous implies readiness to betray trust or confidence.
    • a treacherous adviser
perfidious adds to faithless the implication of an incapacity for fidelity or reliability.
    • a perfidious double-crosser

TREACHEROUS Defined for English Language Learners


Definition of treacherous for English Language Learners

  • : not able to be trusted : showing that someone cannot be trusted

  • : very dangerous and difficult to deal with

TREACHEROUS Defined for Kids


adjective treach·er·ous \ ˈtre-chə-rəs \

Definition of treacherous for Students

1 : not safe because of hidden dangers
  • This was a treacherous road at night …
  • —John Reynolds Gardiner, Stone Fox
2 : not trustworthy : guilty of betrayal or likely to betray
  • a treacherous enemy



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very hard to disturb or upset

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