unstable
adjective
un·sta·ble
ˌən-ˈstā-bəl 
: 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
unstableness
noun
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
To address such an unstable yet technical landscape, businesses ‘curate’ teams of experts and ask them to work together.
—
London Business School, Forbes, 9 Jan. 2025
An underground glow In fungi, the key step towards bioluminescence occurs when the enzyme luciferase converts light-emitting compound called luciferin into an unstable product.
—Laura Baisas, Popular Science, 9 Jan. 2025
If finance were just a morality tale, in which there were villains who need to be contained, the remedy for unstable finance would be extremely simple: tough regulation.
—The New Yorker, 8 Jan. 2025
Free radicals are unstable molecules created in the environment via pollutants and the sun’s UV rays.
—Kristin Canning, SELF, 7 Jan. 2025
See all Example Sentences for unstable 
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London Business School, Forbes, 9 Jan. 2025
An underground glow In fungi, the key step towards bioluminescence occurs when the enzyme luciferase converts light-emitting compound called luciferin into an unstable product.
—Laura Baisas, Popular Science, 9 Jan. 2025
If finance were just a morality tale, in which there were villains who need to be contained, the remedy for unstable finance would be extremely simple: tough regulation.
—The New Yorker, 8 Jan. 2025
Free radicals are unstable molecules created in the environment via pollutants and the sun’s UV rays.
—Kristin Canning, SELF, 7 Jan. 2025
See all Example Sentences for unstable
Dictionary Entries Near unstable
Cite this Entry
“Unstable.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/unstable. Accessed 18 Jan. 2025.
Copy CitationKids Definition
unstable
adjective
un·sta·ble
ˌən-ˈstā-bəl
ˈən-
1
: not stable : not firm or fixed : fluctuating
unstable prices
an unstable tower
unstable weather
2
: readily changing in chemical composition or physical state or properties (as by breaking down into parts)
an unstable atomic nucleus
Medical Definition
unstable
adjective
un·sta·ble
-ˈstā-bəl
: 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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