treacherous
TREHT-shuh-ruhs
Treacherous (adj) means willing to betray trust; disloyal and deceitful. Example: “His treacherous business partner sold the company's secrets to a rival.”
adj
1
Willing to betray trust; disloyal and deceitful.
"His treacherous business partner sold the company's secrets to a rival."
2
Dangerous or unreliable, especially in a way that isn't obvious at first.
"Work on the muskeg resulted in the formation in the first instance, and later in lengths of newly-laid track disappearing without trace into the treacherous bog."
— , New Railways in Quebec (1959)
"There are many treacherous paths leading toward history’s realms of darkness, but when it comes to routes hacked out by imperialist powers in the Congo, we really do seem near darkness’s heart."
— Edward Rothstein, Casting a Sliver of Light on the Heart of Darkness (2009)
"a treacherous mountain trail"
"The icy mountain road was treacherous after dark."
How to use treacherous
Learner’s notesIn plain EnglishTreacherous describes either a person who betrays trust or a situation/place that's secretly dangerous.
Common pairings
treacherous conditions
treacherous waters
a treacherous friend
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Word forms
- Comparative
- more treacherous
- Superlative
- most treacherous
Fill the gap
Can you complete this real example?
His _____ business partner sold the company's secrets to a rival.
Etymology
From Old French trecheros, "deceitful" — related to "treachery."
Synonyms
View more →Antonyms
Related words
Rhymes for treacherous
See all rhymes for treacherous →Frequently asked questions
What does “treacherous” mean?
The word “treacherous” means willing to betray trust; disloyal and deceitful. In plain terms, treacherous describes either a person who betrays trust or a situation/place that's secretly dangerous.
How do you pronounce “treacherous”?
“Treacherous” is pronounced TREHT-shuh-ruhs (/ˈtɹɛt͡ʃəɹəs/ in IPA).
How do you use “treacherous” in a sentence?
Here is “treacherous” used in a sentence: “His treacherous business partner sold the company's secrets to a rival.”
What is another word for “treacherous”?
Words with a similar meaning to “treacherous” include booky, dastardly, disleal, disloyal, double-dealing and double-crossing.
What is the opposite of “treacherous”?
The opposite of “treacherous” — its antonyms — are faithful, fidelitous, leal, loyal and steadfast.
What part of speech is “treacherous”?
“Treacherous” is an adjective.
Where does the word “treacherous” come from?
The word “treacherous” comes from Old French. From Old French trecheros, "deceitful" — related to "treachery.".
Is “treacherous” a common word?
“Treacherous” is an uncommon word in modern English, usually learned at around the C2 level.
