Synonyms of unstable

unstable

adjective

ˌən-ˈstā-bəl 

1

as in unsteady

not being in or able to maintain a state of balance

the minute we put the books down on the unstable desk, the whole stack went crashing to the floor

Synonyms & Similar Words

• unsteady
• precarious
• rocky
• unbalanced
• uneven
• shaky
• wobbly
• insecure
• wonky
• tipsy
• infirm
• tippy
• rickety
• unsound
• tottering
• lopsided
• doddering
• teetering
• wavery
• awry
• tottery
• doddery
• jiggly
• askew
• jiggling
• staggery
• off-kilter
• cockeyed

Antonyms & Near Antonyms

• stable
• steady
• stabilized
• balanced
• level
• substantial
• straight
• equilibrated
• even
• sound
• sturdy

2

as in volatile

likely to change frequently, suddenly, or unexpectedly

financial investors don't like an unstable economy

Synonyms & Similar Words

• volatile
• unpredictable
• inconsistent
• changeful
• uncertain
• variable
• unsettled
• mercurial
• mutable
• fluctuating
• capricious
• inconstant
• changeable
• temperamental
• unsteady
• fickle
• erratic
• unreliable
• shaky
• fluid
• up in the air
• skittish
• random
• haphazard
• scattered
• flickery
• arbitrary
• aimless
• ambivalent
• untrustworthy
• slapdash
• undependable
• stray
• irregular
• dicey
• hit-or-miss
• desultory
• versatile
• adaptable
• vacillating
• mobile
• protean
• wavering
• hesitating
• shilly-shallying
• shilly-shally

Antonyms & Near Antonyms

• stable
• constant
• certain
• steady
• predictable
• stationary
• unchanging
• invariable
• unchangeable
• immutable
• settled
• uniform
• permanent
• even
• persistent
• changeless
• durable
• unvarying
• lasting
• reliable
• equable
• abiding
• dependable
• true
• sure
• trustworthy
• trusty
• tried
• tried-and-true

3

as in changing

not staying constant

unstable temperatures are not ideal storage conditions for wine

Synonyms & Similar Words

• changing
• uneven
• varying
• volatile
• unequal
• erratic
• changeful
• inconsistent
• unsteady
• fluctuating
• irregular
• uncertain
• variable
• mercurial
• capricious
• unsettled
• changeable
• fickle
• mutable
• inconstant
• fluid
• choppy

Antonyms & Near Antonyms

• stable
• constant
• steady
• unchanging
• regular
• changeless
• unvarying

Synonym Chooser

How does the adjective unstable differ from other similar words?

Some common synonyms of unstable are capricious, fickle, inconstant, and mercurial. While all these words mean "lacking firmness or steadiness (as in purpose or devotion)," unstable implies an incapacity for remaining in a fixed position or steady course and applies especially to a lack of emotional balance.

too unstable to hold a job

When can capricious be used instead of unstable?

The synonyms capricious and unstable are sometimes interchangeable, but capricious suggests motivation by sudden whim or fancy and stresses unpredictability.

an utterly capricious critic

When would fickle be a good substitute for unstable?

The words fickle and unstable can be used in similar contexts, but fickle suggests unreliability because of perverse changeability and incapacity for steadfastness.

performers discover how fickle fans can be

When is inconstant a more appropriate choice than unstable?

The words inconstant and unstable are synonyms, but do differ in nuance. Specifically, inconstant implies an incapacity for steadiness and an inherent tendency to change.

an inconstant friend

When could mercurial be used to replace unstable?

Although the words mercurial and unstable have much in common, mercurial implies a rapid changeability in mood.

made anxious by her boss's mercurial temperament

Example Sentences

Recent Examples of unstable

There are avalanche warnings for certain elevations and slopes east of Salt Lake City because of new snow brought by heavy snow and high winds that are creating unstable snow, the Utah Avalanche Center said in a message relayed by the National Weather Service. —Lindsay Good, NBC news, 20 Feb. 2026

The Sierra Avalanche Center said the threat of more avalanches remained Wednesday and the snowpack was unstable and unpredictable in an area known for steep, craggy cliffs. —Arkansas Online, 19 Feb. 2026

However, the technology has not reached its potential due to issues such as unstable lithium plating and reactions at the electrode-electrolyte interface, which shorten battery life and raise safety concerns. —Ameya Paleja, Interesting Engineering, 19 Feb. 2026

This combination of an unstable base below a thick layer of unconsolidated fresh snow is one of the most dangerous causes of snow avalanches in the mountains, Swain says. —Tom Metcalfe, Scientific American, 18 Feb. 2026