unstable

[uhn-stey-buhl] / ʌnˈsteɪ bəl /

ADJECTIVE

doubtful

Synonyms

STRONGEST

ambiguous changeable erratic fickle insecure irrational precarious risky rocky sensitive shaky slippery ticklish tricky uncertain unpredictable unsettled unsteady volatile weak wobbly

WEAK

borderline capricious dizzy dubious fitful fluctuating giddy inconsistent inconstant lubricious mercurial mobile movable moving mutable not fixed rickety shifty suspect teetering temperamental untrustworthy vacillating variable wavering weaving wiggly

Antonyms

STRONGEST

certain clear confident constant definite dependable easy firm guarded happy predictable protected reliable safe secure sound stable steady strong sure unchanging unshaky

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

While fluid membranes support fusion, they can also become unstable during freeze-thaw-induced stress, leading to leakage.

From Science Daily • Apr. 29, 2026

When the stakes are described in life or death terms, the mentally unstable convince themselves of their own righteous cause.

From The Wall Street Journal • Apr. 26, 2026

When the earth layers of the cliffside move, oxygen can interact with unstable compounds in the rocks — including iron sulfides — which produces a lot of heat during the oxidation process.

From Los Angeles Times • Apr. 24, 2026

By the time the doctor had logged there was no fetal heartbeat, the medical record shows, Crain was too unstable for surgery.

From Salon • Apr. 20, 2026

I was beginning to feel that I had finally found a place to stay, a place that was not so unstable or corrupt or controlling that I could actually belong there.

From "Allegiant" by Veronica Roth

Vocabulary lists containing unstable

100 SAT Words Beginning with "U"

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Engineering - Introductory

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Civil Engineering

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