treacherous

adjective

treach·​er·​ous ˈtre-chə-rəs 

ˈtrech-rəs

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

treacherously adverb

treacherousness noun

Synonyms

• disloyal
• faithless
• false
• fickle
• inconstant
• perfidious
• recreant
• traitorous
• unfaithful
• untrue

Choose the Right Synonym for 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

Examples of treacherous in a Sentence

a treacherous act of betrayal

They were not prepared to hike over such treacherous terrain.

The snow made their hike all the more treacherous.

Discussions about money can lead couples into treacherous territory.

Recent Examples on the Web

When a bad market happened, her plan—her map—suddenly became treacherous and no longer worked out mathematically. —Roger Whitney, Forbes, 23 Oct. 2024

Entering their treacherous world, along with his wife (Victoria Smurfit) and daughter (Bella Maclean), is hard-hitting TV journalist Declan O’Hara (Aidan Turner), lured from the upright BBC to Lord Tony’s fictional commercial network. —Meredith Blake, Los Angeles Times, 18 Oct. 2024

The Cape Disappointment Lighthouse, perched on the southwestern tip of Washington, has a rich history as the first lighthouse in the state, guiding sailors through the treacherous Columbia River Bar since it was built in 1856. —Christine Clarridge, Axios, 18 Oct. 2024

First, that the new generation of case followers not lose sight of the seriousness of their crime and second, that having hope for the brothers at this point in their lives, now in their 50s, can be a treacherous thing. —Jackie Strause, The Hollywood Reporter, 10 Oct. 2024

Word History

First Known Use

14th century, in the meaning defined at sense 2

Kids Definition

treacherous

adjective

treach·​er·​ous ˈtrech-(ə-)rəs 

1

a

: guilty of treachery

b

: likely to betray : unreliable

a treacherous memory

2

: giving a false appearance of safety or solidity

a treacherous stretch of bog

treacherously adverb