instability
Americannoun
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the quality or state of being unstable; lack of stability or firmness.
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the tendency to behave in an unpredictable, changeable, or erratic manner.
emotional instability.
noun
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lack of stability or steadiness
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tendency to variable or unpredictable behaviour
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physics a fast growing disturbance or wave in a plasma
Etymology
Origin of instability
1375–1425; late Middle English instabilite < Latin instabilitās. See in- 3, stability
Explanation
Instability is the quality of not being stable, balanced, or predictable. If you've ever walked out onto a diving board, you've probably noticed its instability — meaning the board bends and bounces as you move. Instability comes from the Middle French word instabilite, meaning "unsteadiness." Instability can refer to objects that are not stable, but it can also describe unpredictable situations or relationships. For example, you might hear people talk about economic instability. Or if your behavior at school grows erratic and unpredictable, you might be asked to speak to a therapist about your psychological instability.
Vocabulary lists containing instability
Southeast Asia - Middle School
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Southeast Asia - High School
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Second Democratic Debate 20 words
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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.
"And on the route, it encounters that instability zone around binaries, where three-body effects kick into place and gravitationally clear out the zone."
From Science Daily • Apr. 19, 2026
Four recently published UCLA-led studies draw a direct line between climate disasters, housing instability and homelessness, with researchers pointing to the 2025 Los Angeles County wildfires as one of the starkest recent examples.
From Los Angeles Times • Apr. 16, 2026
It’s a remarkable feat in the face of the ongoing instability in the Middle East.
From Barron's • Apr. 15, 2026
McKechnie - who once said he treats "broken-down athletes who are almost like reclamation projects" - had discovered Hargreaves' knee issues were caused by pelvic instability and therefore got him working to strengthen his core.
From BBC • Apr. 14, 2026
But he may also, to some extent, be a beneficiary of this ongoing instability.
From "Drama High" by Michael Sokolove
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
