unstable

adjective
un·​sta·​ble | \ ˌən-ˈstā-bəl \

Definition of unstable

: not stable : not firm or fixed : not constant: such as
a : not steady in action or movement : irregular an unstable pulse
b : wavering in purpose or intent : vacillating
c : lacking steadiness : apt to move, sway, or fall an unstable tower
d(1) : liable to change or alteration an unstable economy unstable weather
(2) : readily changing (as by decomposing) in chemical or physical composition or in biological activity
e : characterized by lack of emotional control

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Other Words from unstable

unstableness noun
unstably \ ˌən-​ˈstā-​b(ə-​)lē \ adverb

Synonyms & Antonyms for unstable

Synonyms

unbalanced, unsteady

Antonyms

balanced, equilibrated, stabilized, stable, steady

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Choose the Right Synonym for unstable

inconstant, fickle, capricious, mercurial, unstable mean lacking firmness or steadiness (as in purpose or devotion). inconstant implies an incapacity for steadiness and an inherent tendency to change. an inconstant friend fickle suggests unreliability because of perverse changeability and incapacity for steadfastness. performers discover how fickle fans can be capricious suggests motivation by sudden whim or fancy and stresses unpredictability. an utterly capricious critic mercurial implies a rapid changeability in mood. made anxious by her boss's mercurial temperament 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

Examples of unstable in a Sentence

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

Recent Examples on the Web

However, a harmonic oscillation began at 265 seconds into the flight and grew increasingly unstable until 474 seconds, when the Kestrel engine shut down early. Eric Berger, Ars Technica, "Inside the eight desperate weeks that saved SpaceX from ruin," 21 Sep. 2018 The parents of a California toddler crushed to death last year by an Ikea dresser have filed suit against the retailer, claiming the company knew for years its dressers were unstable but neglected to redesign them. Tricia L. Nadolny, Philly.com, "Ikea facing new suit from child's death," 21 June 2018 It is known to be losing ice rapidly because it is being melted from below by warm ocean waters, a process that is rendering its largest glaciers unstable. Chris Mooney, courant.com, "Antarctic ice loss has tripled in a decade. If that continues we are in serious trouble.," 13 June 2018 If Europe’s most important parties crumble or become unstable, to be replaced by new parties that lack institutional memory and resources, that leaves the system as a whole less stable, regardless of what kind of politics its leaders embrace. Amanda Taub, New York Times, "Paving Over Differences, Europe’s Centrists Risk Rougher Ride," 11 Feb. 2018 It’ll be taken apart and thoroughly scanned to understand how the harsh conditions of space — unpredictable levels of radiation, subatomic particles, and unstable power — can affect a commercial off-the-shelf computer. Mary Beth Griggs, The Verge, "A supercomputer on the ISS will soon be open for science experiments," 1 Nov. 2018 Acting Police Commissioner Gary Tuggle said the youngster remains in critical and unstable condition at a city hospital. Washington Post, "7-year-old Baltimore girl shot in back of car," 7 July 2018 And no person should feel precarious or unstable in their access to housing as our economy develops. NBC News, "Meet the Press - July 1, 2018," 1 July 2018 Mr Ortega’s brutality has exposed that bargain as morally bankrupt and politically unstable. The Economist, "Time is running out for Nicaragua’s President Daniel Ortega," 9 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'unstable.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of unstable

13th century, in the meaning defined above

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Statistics for unstable

Last Updated

5 Feb 2019

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Time Traveler for unstable

The first known use of unstable was in the 13th century

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More Definitions for unstable

unstable

adjective

English Language Learners Definition of unstable

: likely to change
: not emotionally or mentally healthy
: not held in a secure position : likely to move or fall

unstable

adjective
un·​sta·​ble | \ ˌən-ˈstā-bəl \

Kids Definition of unstable

: not stable an unstable boat

unstable

adjective
un·​sta·​ble | \ -ˈstā-bəl \

Medical Definition of unstable

: not stable: as
a : characterized by frequent or unpredictable changes a patient in unstable condition
b : readily changing (as by decomposing) in chemical composition or biological activity unstable compounds
c : characterized by lack of emotional control or stability

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More from Merriam-Webster on unstable

Rhyming Dictionary: Words that rhyme with unstable

Thesaurus: All synonyms and antonyms for unstable

Spanish Central: Translation of unstable

Nglish: Translation of unstable for Spanish Speakers

Comments on unstable

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