You can describe something as unstable if it is likely to change suddenly, especially if this creates difficulty or danger.
After the fall of Pitt in 1801 there was a decade of unstable government.
The situation is unstable and potentially dangerous.
Synonyms: changeable, volatile, unpredictable, variable More Synonyms of unstable
2. adjective
Unstable objects are likely to move or fall.
Both clay and sandstone are unstable rock formations.
3. adjective
If people are unstable, their emotions and behaviour keep changing because their minds are disturbed or upset.
He was emotionally unstable.
Coleridge was also a highly unstable person.
Synonyms: unpredictable, irrational, erratic, inconsistent More Synonyms of unstable
More Synonyms of unstable
unstable in British English
(ʌnˈsteɪbəl)
adjective
1.
lacking stability, fixity, or firmness
2.
disposed to temperamental, emotional, or psychological variability
3.
(of a chemical compound) readily decomposing
4. physics
a.
(of an elementary particle) having a very short lifetime
b.
spontaneously decomposing by nuclear decay; radioactive
an unstable nuclide
5. electronics
(of an electrical circuit, mechanical body, etc) having a tendency to self-oscillation
Derived forms
unstableness (unˈstableness)
noun
unstably (unˈstably)
adverb
unstable in American English
(ʌnˈsteɪbəl)
adjective
not stable
; specif.,
a.
not fixed, firm, or steady; easily upset or unbalanced
b.
changeable; variable; fluctuating
c.
unreliable; fickle
d.
emotionally unsettled
e. Chemistry
tending to decompose or change into other compounds
SIMILAR WORDS: inˈconstant
Derived forms
unstableness (unˈstableness)
noun
unstably (unˈstably)
adverb
Word origin
ME
Examples of 'unstable' in a sentence
unstable
You are emotionally unstable because of stuff that happened to you way back.
The Sun (2012)
The result is a spread of weak minority governments and unstable coalitions.
Times, Sunday Times (2006)
The world is becoming a more dangerous and unstable place.
The Sun (2010)
This has long been a potentially unstable combination.
Times, Sunday Times (2006)
This results in better outcomes after a patient suffers from unstable angina or a heart attack.
Times, Sunday Times (2015)
To be doing so while also becoming more mentally unstable would really be depressing.
Times, Sunday Times (2008)
Any man who would wish to sport a picture of a battered woman must be emotionally unstable.
The Sun (2012)
The second is less common and occurs at rest and is known as unstable angina.
Wallace, Louise M & Bundy, Christine Coping with Angina (1990)
Police said he was known to them as a petty offender and appeared to be mentally unstable.
Times, Sunday Times (2013)
It is also an aid in treating patients with small heart attacks or unstable angina.
Pantano, James A. (MD) Living with Angina (1991)
He became paranoid and emotionally unstable.
The Sun (2016)
That's an unstable situation for at least two months.
The Sun (2016)
It would be obvious that such a Government would be unstable and unable to implement its programme.
Times, Sunday Times (2014)
So if the situation is unstable and unpredictable, is there anything that can be done?
Times, Sunday Times (2013)
So in an increasingly dangerous and unstable world can Britain still defend itself against the mounting military threats?
Times, Sunday Times (2015)
In total, there have been fewer than six years of being governed this way and these periods proved highly unstable.
Times, Sunday Times (2015)
This situation was extremely unstable.
Times, Sunday Times (2011)
DSK's defenders paint her as fragile and emotionally unstable.
Times, Sunday Times (2011)
Their work is probably part-time, and highly unstable.
Appelbaum, Richard P. Sociology (1995)
The monarchy was overthrown in 1973, and since then government has been unstable.
Thackrah, J. R. Twentieth Century History - Basic Facts (1985)
Yet convincing people voluntarily to declare income and pay tax, a practice few remember after three decades of violence and unstable governments, is no easy task.
Times, Sunday Times (2012)
In other languages
unstable
British English: unstable /ʌnˈsteɪbl/ ADJECTIVE
You can describe something as unstable if it is likely to change suddenly, especially if this creates difficulty.
The situation is unstable and dangerous.
American English: unstable
Arabic: غَيْرُ مُسْتَقِرّ
Brazilian Portuguese: instável
Chinese: 不稳定的
Croatian: nestabilan
Czech: nestabilní
Danish: ustabil
Dutch: onstabiel
European Spanish: inestable
Finnish: horjuva
French: instable
German: instabil
Greek: ανισόρροπος
Italian: instabile
Japanese: 不安定な
Korean: 불안정한
Norwegian: ustabil
Polish: chwiejny
European Portuguese: instável
Romanian: instabil
Russian: нестабильный
Latin American Spanish: inestable
Swedish: instabil
Thai: ไม่มั่นคง
Turkish: dengesiz
Ukrainian: нестабільний
Vietnamese: không ổn định
Chinese translation of 'unstable'
unstable
(ʌnˈsteɪbl)
adj
[ladder]不牢固的 (bù láogù de)
[government, situation]不稳(穩)固的 (bù wěngù de)
[person]反复(復)无(無)常的 (fǎnfù wú cháng de)
(Chem, Phys)[substance]不稳(穩)定的 (bù wěndìng de)
1 (adjective)
Definition
likely to change suddenly and create difficulties or danger
The situation is unstable and potentially dangerous.
Synonyms
changeable
He was a man of changeable moods.
The forecast is for changeable weather.
volatile
There have been riots before and the situation is volatile.
unpredictable
Britain's notoriously unpredictable weather
variable
Weather conditions are variable and change from day to day.
fluctuating
unsteady
His unsteady relationship with his flatmates incited him to move out.
fitful
He drifted off into a fitful sleep.
inconstant
Opposites
stable
,
steady
,
predictable
,
constant
2 (adjective)
Definition
not firmly fixed and likely to wobble or fall
a house built on unstable foundations
Synonyms
insecure
low-paid, insecure jobs
shaky
Our house will remain on shaky foundations unless the architect sorts out the basement.
precarious
They crawled up a precarious rope ladder.
unsettled
The unsettled political scene worries some investors.
wobbly
I was sitting on a wobbly plastic chair.
tottering
rickety
She climbed the rickety wooden stairway.
unsteady
a slightly unsteady item of furniture
not fixed
3 (adjective)
Definition
(of a person) having abrupt changes of mood or behaviour
He was emotionally unstable.
Synonyms
unpredictable
irrational
erratic
the erratic nature of our recent weather
inconsistent
You are inconsistent and unpredictable.
unreliable
She had proved to be an unreliable witness and had lied to police.
temperamental
The patient was given to temperamental outbursts and paranoia.
capricious
capricious mood swings
changeable
untrustworthy
His opponents still say he's a fundamentally untrustworthy figure.
vacillating
Opposites
rational
,
level-headed
,
stable
,
consistent
,
reliable
,
trustworthy
Additional synonyms
in the sense of capricious
Definition
having a tendency to sudden unpredictable changes of attitude or behaviour
capricious mood swings
Synonyms
unpredictable,
variable,
unstable,
inconsistent,
erratic,
quirky,
fickle,
impulsive,
mercurial,
freakish,
fitful,
inconstant,
changeful
in the sense of erratic
Definition
irregular or unpredictable
the erratic nature of our recent weather
Synonyms
unpredictable,
variable,
unstable,
irregular,
shifting,
eccentric,
abnormal,
inconsistent,
uneven,
unreliable,
wayward,
capricious,
desultory,
changeable,
aberrant,
fitful,
inconstant
in the sense of fitful
Definition
occurring in irregular spells
He drifted off into a fitful sleep.
Synonyms
irregular,
broken,
disturbed,
erratic,
variable,
flickering,
unstable,
uneven,
fluctuating,
sporadic,
intermittent,
impulsive,
haphazard,
desultory,
spasmodic,
inconstant
Synonyms of 'unstable'
unstable
Explore 'unstable' in the dictionary
Additional synonyms
in the sense of inconsistent
Definition
unstable or changeable in behaviour or mood
You are inconsistent and unpredictable.
Synonyms
changeable,
variable,
unpredictable,
unstable,
irregular,
erratic,
uneven,
fickle,
capricious,
unsteady,
inconstant
in the sense of inconstant
Definition
variable
Synonyms
unreliable,
variable,
uncertain,
volatile,
unsettled,
unstable,
inconsistent,
erratic,
wavering,
uneven,
fluctuating,
wayward,
fickle,
temperamental,
mercurial,
capricious,
unsteady,
changeable,
vacillating,
blowing hot and cold (informal),
mutable,
irresolute,
undependable,
changeful,
vagarious (rare)
in the sense of precarious
Definition
(of a position or situation) dangerous or insecure
They crawled up a precarious rope ladder.
Synonyms
dangerous,
unstable,
shaky,
slippery,
insecure,
unsafe,
unreliable,
unsteady
in the sense of rickety
Definition
likely to collapse or break
She climbed the rickety wooden stairway.
Synonyms
shaky,
broken,
weak,
broken-down,
frail,
insecure,
feeble,
precarious,
derelict,
flimsy,
wobbly,
imperfect,
tottering,
ramshackle,
dilapidated,
decrepit,
unsteady,
unsound,
infirm,
jerry-built
in the sense of shaky
Definition
weak and unsteady, esp. due to illness or shock
Our house will remain on shaky foundations unless the architect sorts out the basement.
Synonyms
unstable,
weak,
precarious,
tottering,
ramshackle,
dilapidated,
rickety,
unsteady,
wonky (British, informal)
in the sense of temperamental
Definition
(of a person) tending to be moody and have sudden outbursts of anger
The patient was given to temperamental outbursts and paranoia.
Synonyms
moody,
emotional,
touchy,
sensitive,
explosive,
passionate,
volatile,
fiery,
impatient,
erratic,
irritable,
mercurial,
excitable,
capricious,
petulant,
hot-headed,
chippy (informal),
hypersensitive,
highly strung,
easily upset,
unstable
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 unsettled
Definition
lacking order or stability
The unsettled political scene worries some investors.
Synonyms
unstable,
shaky,
insecure,
disorderly,
unsteady
in the sense of unsteady
His unsteady relationship with his flatmates incited him to move out.
Synonyms
erratic,
unpredictable,
volatile,
unsettled,
wavering,
unreliable,
temperamental,
changeable,
vacillating,
flighty,
inconstant
in the sense of unsteady
Definition
not securely fixed
a slightly unsteady item of furniture
Synonyms
unstable,
shaky,
insecure,
unsafe,
precarious,
treacherous,
rickety,
infirm
Additional synonyms
in the sense of untrustworthy
Definition
unreliable and not able to be trusted
His opponents still say he's a fundamentally untrustworthy figure.
Synonyms
unreliable,
treacherous,
deceitful,
false,
tricky,
slippery,
untrue,
dishonest,
fickle,
devious,
unfaithful,
capricious,
two-faced,
disloyal,
faithless,
fair-weather,
fly-by-night (informal),
undependable,
not to be depended on,
untrusty
in the sense of variable
Definition
likely to change at any time
Weather conditions are variable and change from day to day.
Synonyms
changeable,
unstable,
fluctuating,
shifting,
flexible,
wavering,
uneven,
fickle,
temperamental,
mercurial,
capricious,
unsteady,
protean,
vacillating,
fitful,
mutable,
inconstant,
chameleonic
in the sense of volatile
Definition
(of circumstances) liable to sudden change
There have been riots before and the situation is volatile.