If you describe someone as treacherous, you mean that they are likely to betray you and cannot be trusted.
[disapproval]
He publicly left the party and denounced its treacherous leaders.
The President spoke of the treacherous intentions of the enemy.
Synonyms: disloyal, deceitful, untrustworthy, duplicitous More Synonyms of treacherous
2. adjective
If you say that something is treacherous, you mean that it is very dangerous and unpredictable.
The current of the river is fast flowing and treacherous.
They made the treacherous journey across stormy seas in rotten boats.
Synonyms: dangerous, tricky, risky, unstable More Synonyms of treacherous
treacherous in British English
(ˈtrɛtʃərəs)
adjective
1.
betraying or likely to betray faith or confidence
2.
unstable, unreliable, or dangerous
treacherous weather
treacherous ground
Derived forms
treacherously (ˈtreacherously)
adverb
treacherousness (ˈtreacherousness)
noun
treacherous in American English
(ˈtrɛtʃərəs)
adjective
1.
characterized by treachery; traitorous; disloyal; perfidious
2.
giving a false appearance of safety or reliability; untrustworthy or insecure
treacherous rocks
SIMILAR WORDS: ˈfaithless
Derived forms
treacherously (ˈtreacherously)
adverb
treacherousness (ˈtreacherousness)
noun
Word origin
ME trecherous < OFr trecheros
Examples of 'treacherous' in a sentence
treacherous
Motorists were told to expect treacherous driving conditions today as freezing fog and ice continued to cause problems in parts of England.
Times, Sunday Times (2016)
It will make roads treacherous and can cause an instant glaze over cars.
The Sun (2012)
Motorists were warned to make only essential journeys because of treacherous icy roads.
The Sun (2009)
Many drivers had lucky escapes in treacherous conditions.
The Sun (2008)
It was a treacherous journey that only one in four crews survived.
Times, Sunday Times (2015)
Its driver had been struggling in treacherous road conditions.
The Sun (2015)
Celebrities were not immune to the treacherous conditions.
Times, Sunday Times (2013)
So what makes it so treacherous?
Times, Sunday Times (2012)
Care in treacherous conditions is advisable.
Times, Sunday Times (2010)
Conditions are as unpredictable and treacherous as the Arctic.
Times, Sunday Times (2012)
When spilt on the roads, it makes driving conditions treacherous.
Times, Sunday Times (2007)
The getaway is also expected to be tough on the roads, with treacherous driving conditions.
The Sun (2014)
Police urged well-meaning locals planning their own search to abandon the idea due to the treacherous conditions.
The Sun (2012)
And emergency services had one of their busiest days of the year as scores of motorists skidded into each other in the treacherous conditions.
The Sun (2008)
Road conditions remained treacherous last night and Cumbria police warned motorists not to drive unless it was absolutely necessary.
Times, Sunday Times (2013)
With the current treacherous planetary setup, you'd best reflect before going to battle.
Times, Sunday Times (2013)
It promises to be the hardest, most treacherous, journey of their lives.
Times, Sunday Times (2007)
When the treacherous currents mangled oil platform cables and pipes, companies would send the strapping Australian into the murky depths to sort them out.
Times, Sunday Times (2014)
In other languages
treacherous
British English: treacherous ADJECTIVE
If you describe someone as treacherous, you mean that they are likely to betray you and cannot be trusted.
He publicly left the party and denounced its treacherous leaders.
American English: treacherous
Brazilian Portuguese: traiçoeiro
Chinese: 背信弃义的
European Spanish: traidor
French: traître
German: verräterisch
Italian: infido
Japanese: 裏切りをする
Korean: 기만적인
European Portuguese: traiçoeiro
Latin American Spanish: traicionero
Chinese translation of 'treacherous'
treacherous
(ˈtrɛtʃərəs)
adj
[person]不忠的 (bù zhōng de)
[ground, conditions, current]危险(險)的 (wēixiǎn de)
1 (adjective)
Definition
disloyal and untrustworthy
The President spoke of the treacherous intentions of the enemy.
Synonyms
disloyal
He proved to be an untrustworthy and disloyal ally.
deceitful
The ambassador called the report deceitful and misleading.
untrustworthy
His opponents still say he's a fundamentally untrustworthy figure.
duplicitous
false
She was a false friend, envious of her lifestyle and her success.
untrue
untrue to the basic tenets of socialism
unreliable
She had proved to be an unreliable witness and had lied to police.
unfaithful
They denounced him as unfaithful to the traditions of the Society.
faithless
She decided to divorce her increasingly faithless and unreliable husband.
double-crossing (informal)
double-dealing
Slimy, double-dealing politicians have betrayed us all.
perfidious (literary)
She says that politicians are a perfidious breed.
traitorous
the betrayal of men by their most traitorous companions
treasonable
They were brought to trial for treasonable conspiracy.
recreant (archaic)
Opposites
true
,
reliable
,
loyal
,
faithful
,
dependable
,
trustworthy
2 (adjective)
Definition
unreliable or dangerous, esp. because of sudden changes
The current of the river is fast-flowing and treacherous.
Synonyms
dangerous
a dangerous undertaking
tricky
They could encounter some tricky political manoeuvring.
risky
It is a very risky business.
unstable
He was emotionally unstable.
hazardous
Below decks was hazardous in very heavy weather.
icy
an icy road
slippery
The floor was wet and slippery.
unsafe
Critics claim the trucks are unsafe.
unreliable
precarious
Our financial situation had become precarious.
deceptive
Her worst fault is a strongly deceptive streak.
perilous
a perilous journey across the war-zone
slippy (informal, dialect)
Opposites
safe
,
reliable
Additional synonyms
in the sense of deceitful
Definition
full of deceit
The ambassador called the report deceitful and misleading.
Synonyms
dishonest,
false,
deceiving,
fraudulent,
treacherous,
deceptive,
hypocritical,
counterfeit,
crafty,
sneaky,
illusory,
two-faced,
disingenuous,
untrustworthy,
underhand,
insincere,
double-dealing,
duplicitous,
fallacious,
guileful,
knavish (archaic)
in the sense of deceptive
Her worst fault is a strongly deceptive streak.
Synonyms
dishonest,
deceiving,
fraudulent,
treacherous,
hypocritical,
crafty,
sneaky,
two-faced,
disingenuous,
deceitful,
untrustworthy,
underhand,
insincere,
duplicitous,
guileful
in the sense of double-dealing
Slimy, double-dealing politicians have betrayed us all.
Synonyms
treacherous,
lying,
cheating,
tricky,
crooked (informal),
fraudulent,
two-timing (informal),
dishonest,
hypocritical,
wily,
swindling,
sneaky,
two-faced,
deceitful,
untrustworthy,
duplicitous,
perfidious (literary),
underhanded
Synonyms of 'treacherous'
treacherous
Explore 'treacherous' in the dictionary
Additional synonyms
in the sense of faithless
Definition
treacherous or disloyal
She decided to divorce her increasingly faithless and unreliable husband.
Synonyms
disloyal,
unreliable,
unfaithful,
untrustworthy,
doubting,
false,
untrue,
treacherous,
dishonest,
fickle,
perfidious (literary),
untruthful,
traitorous,
unbelieving,
inconstant,
false-hearted,
recreant (archaic)
in the sense of false
She was a false friend, envious of her lifestyle and her success.
Synonyms
treacherous,
lying,
deceiving,
unreliable,
two-timing (informal),
dishonest,
deceptive,
hypocritical,
unfaithful,
two-faced,
disloyal,
unsound,
deceitful,
faithless,
untrustworthy,
insincere,
double-dealing,
dishonourable,
duplicitous,
mendacious,
perfidious (literary),
treasonable,
traitorous,
inconstant,
delusive,
false-hearted
in the sense of hazardous
Definition
involving great risk
Below decks was hazardous in very heavy weather.
Synonyms
dangerous,
risky,
difficult,
uncertain,
unpredictable,
insecure,
hairy (slang),
unsafe,
precarious,
perilous,
parlous (archaic, humorous),
dicey (informal, British),
fraught with danger,
chancy (informal)
in the sense of icy
Definition
covered with ice
an icy road
Synonyms
slippery,
glassy,
slippy (informal, dialect),
like a sheet of glass,
rimy
in the sense of perfidious
Definition
treacherous or deceitful
She says that politicians are a perfidious breed.
Synonyms
treacherous,
dishonest,
false,
corrupt,
unfaithful,
two-faced,
disloyal,
deceitful,
faithless,
untrustworthy,
double-dealing,
traitorous,
double-faced,
treasonous,
recreant (archaic)
in the sense of perilous
a perilous journey across the war-zone
Synonyms
dangerous,
threatening,
exposed,
vulnerable,
risky,
unsure,
hazardous,
hairy (slang),
unsafe,
precarious,
parlous (archaic),
fraught with danger,
chancy (informal)
in the sense of precarious
Definition
(of a position or situation) dangerous or insecure
Our financial situation had become precarious.
Synonyms
insecure,
dangerous,
uncertain,
tricky,
risky,
doubtful,
dubious,
unsettled,
dodgy (British, Australian, New Zealand, informal),
unstable,
unsure,
hazardous,
shaky,
hairy (slang),
perilous,
touch and go,
dicey (informal, British),
chancy (informal),
built on sand,
shonky (Australian, New Zealand, informal)
in the sense of risky
It is a very risky business.
Synonyms
dangerous,
hazardous,
unsafe,
perilous,
uncertain,
tricky,
dodgy (British, Australian, New Zealand, informal),
precarious,
touch-and-go,
dicey (informal, British),
fraught with danger,
chancy (informal),
shonky (Australian, New Zealand, informal)
in the sense of slippery
Definition
liable or tending to cause objects to slip
The floor was wet and slippery.
Synonyms
smooth,
icy,
greasy,
glassy,
slippy (informal, dialect),
unsafe,
lubricious (rare),
skiddy (informal)
in the sense of traitorous
the betrayal of men by their most traitorous companions
Synonyms
treacherous,
unfaithful,
disloyal,
false,
untrue,
renegade,
faithless,
double-crossing (informal),
double-dealing,
seditious,
perfidious (literary),
apostate,
treasonable
Additional synonyms
in the sense of treasonable
They were brought to trial for treasonable conspiracy.
Synonyms
disloyal,
false,
subversive,
treacherous,
seditious,
mutinous,
perfidious (literary),
traitorous,
treasonous
in the sense of tricky
Definition
sly or wily
They could encounter some tricky political manoeuvring.
Synonyms
crafty,
scheming,
subtle,
cunning,
slippery,
sly,
deceptive,
devious,
wily,
artful,
foxy,
deceitful
in the sense of unfaithful
Definition
not true to a promise or vow
They denounced him as unfaithful to the traditions of the Society.
Synonyms
disloyal,
false,
treacherous,
deceitful,
faithless,
perfidious (literary),
traitorous,
treasonable,
false-hearted,
recreant (archaic)
in the sense of unreliable
Definition
not able to be trusted or relied on
She had proved to be an unreliable witness and had lied to police.
Synonyms
undependable,
irresponsible,
untrustworthy,
unstable,
treacherous,
disreputable,
not conscientious
in the sense of unsafe
Definition
dangerous
Critics claim the trucks are unsafe.
Synonyms
dangerous,
risky,
hazardous,
threatening,
uncertain,
unstable,
insecure,
unreliable,
precarious,
treacherous,
perilous,
unsound
in the sense of unstable
Definition
(of a person) having abrupt changes of mood or behaviour
He was emotionally unstable.
Synonyms
unpredictable,
irrational,
erratic,
inconsistent,
unreliable,
temperamental,
capricious,
changeable,
untrustworthy,
vacillating
in the sense of untrue
Definition
disloyal or unfaithful
untrue to the basic tenets of socialism
Synonyms
unfaithful,
disloyal,
deceitful,
treacherous,
two-faced,
faithless,
false,
untrustworthy,
perfidious (literary),
forsworn,
traitorous,
inconstant
in the sense of untrustworthy
Definition
unreliable and not able to be trusted
His opponents still say he's a fundamentally untrustworthy figure.