fluctuation
noun
fluc·tu·a·tion
ˌflək-chə-ˈwā-shən 
-chü-ˈā-
plural fluctuations
: an act or instance of fluctuating : an irregular shifting back and forth or up and down in the level, strength, or value of something
Small fluctuations in prices are to be expected.
Some fluctuation in real estate values is not unusual.
North American species in general, having contended with blazing July days and frosty September nights as they evolved, are much more tolerant of temperature fluctuations than tropical species are.—
Jonathan Franzen
Jonathan FranzenExamples of fluctuation in a Sentence
political instability that resulted in wild fluctuations in the overseas stock markets
Recent Examples on the Web
Andrii Yalanskyi/500px Interest rates remain top of mind for homebuyers in the new year, especially after years of volatile swings driven by inflation and Federal Reserve rate fluctuations.
—Brendan Dyer, CBS News, 5 Jan. 2026
From curious critters to temperature fluctuations, the conditions in a garden shed aren't always hospitable for your back-stock items.
—Madeline Buiano, Martha Stewart, 4 Jan. 2026
Mulch insulates the roots and crown of the plant, helping to moderate temperature fluctuations and minimize the impacts of freeze-thaw cycles.
—Kim Toscano, Southern Living, 4 Jan. 2026
Researchers in South Korea have developed a mathematical method to control random molecular fluctuations inside living cells, a breakthrough that could help explain why cancer can recur after chemotherapy or why some bacteria survive antibiotic treatment.
—Neetika Walter, Interesting Engineering, 2 Jan. 2026
See All Example Sentences for fluctuation
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Brendan Dyer, CBS News, 5 Jan. 2026
From curious critters to temperature fluctuations, the conditions in a garden shed aren't always hospitable for your back-stock items.
—Madeline Buiano, Martha Stewart, 4 Jan. 2026
Mulch insulates the roots and crown of the plant, helping to moderate temperature fluctuations and minimize the impacts of freeze-thaw cycles.
—Kim Toscano, Southern Living, 4 Jan. 2026
Researchers in South Korea have developed a mathematical method to control random molecular fluctuations inside living cells, a breakthrough that could help explain why cancer can recur after chemotherapy or why some bacteria survive antibiotic treatment.
—Neetika Walter, Interesting Engineering, 2 Jan. 2026
See All Example Sentences for fluctuation
Cite this Entry
“Fluctuation.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/fluctuation. Accessed 6 Jan. 2026.
Copy CitationMedical Definition
fluctuation
noun
fluc·tu·a·tion
ˌflək-chə-ˈwā-shən
1
: a motion like that of waves
especially
: the wavelike motion of a fluid collected in a natural or artificial cavity of the body observed by palpation or percussion
2
a
: a slight and nonheritable variation
especially
: such a variation occurring in response to environmental factors
b
: recurrent and often more or less cyclic alteration (as of form, size, or color of a bodily part)
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