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

For Tesla and other American manufacturers, the path forward is treacherous. —Jackie Snow, Quartz, 28 Apr. 2025

Kang’s character, Lee Kang-su, walks a treacherous line between crime and law enforcement – a balancing act that presented unique acting challenges. —Naman Ramachandran, Variety, 24 Apr. 2025

After the season one finale had separated Spencer and Alex, season two charted the husband and wife taking different, yet both treacherous, journeys to get back to Montana. —Jackie Strause, HollywoodReporter, 16 Apr. 2025

While the prospect of facing Augusta National’s treacherous greens under major championship conditions would be overwhelmingly intimidating for most amateur golfers, McDermott is a unique case, to say the least. —Erik Matuszewski, Forbes.com, 12 Apr. 2025

Word History

First Known Use

14th century, in the meaning defined at sense 2

Rhymes for treacherous

• lecherous

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