un·​sta·​ble | \ ˌən-ˈstā-bəl How to pronounce unstable (audio) \

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

Other Words from unstable

unstableness noun
unstably \ ˌən-​ˈstā-​b(ə-​)lē How to pronounce unstable (audio) \ adverb

Synonyms & Antonyms for unstable



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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 Companies are increasingly being asked to deliver perfect user experiences over public network connections that are inherently unstable. Chris Macfarland, Forbes, 27 May 2022 Are Americans really drastically more mentally unstable than the British? Peter Bergen, CNN, 25 May 2022 Owen is up for the ten-hour surgery to reconnect the arm, but Colin proves to be too unstable to withstand the surgery. Lincee Ray, EW.com, 6 May 2022 Rotunno later argued that the letter demonstrated how confused and unstable Mann had been. Ken Auletta, The New Yorker, 30 May 2022 Researchers who track shifting demographics in the teacher workforce have found that the profession is becoming less experienced and more unstable compared with during the 1980s, a phenomenon that predates the pandemic. Stephen Noonoo, The New Republic, 2 May 2022 Since the Russian attack on Ukraine on Feb. 24, the world has felt even more unstable, as Americans attentively watch for news of a war in Eastern Europe. al, 17 Apr. 2022 Central banks have badly misjudged the economy and mis-calibrated their policies, and the world is a more unstable place as a result. Mike O'sullivan, Forbes, 26 Mar. 2022 How to feed its 1.4 billion people in a more politically unstable world will increasingly become a key task for Beijing. Jacky Wong, WSJ, 8 Mar. 2022 See More

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.

First Known Use of unstable

13th century, in the meaning defined above

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Time Traveler for unstable

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

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Dictionary Entries Near unstable



unstable angina

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Last Updated

18 Jun 2022

Cite this Entry

“Unstable.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/unstable. Accessed 27 Jun. 2022.

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More Definitions for unstable


un·​sta·​ble | \ ˌən-ˈstā-bəl How to pronounce unstable (audio) \

Kids Definition of unstable

: not stable an unstable boat


un·​sta·​ble | \ -ˈstā-bəl How to pronounce unstable (audio) \

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

More from Merriam-Webster on unstable

Nglish: Translation of unstable for Spanish Speakers


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