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

fluctuational

ˌflək-chə-ˈwā-sh(ə-)nəl 

-chü-ˈā-

adjective

Synonyms of fluctuation

• oscillation
• change

Examples of fluctuation in a Sentence

political instability that resulted in wild fluctuations in the overseas stock markets

Recent Examples on the Web

The Science Behind Stress Synchronization A study published in October 2024 found that the heart rate variability (the slight fluctuations between heartbeats) of a dog and its owner can mirror each other. —Alyce Collins, MSNBC Newsweek, 30 Nov. 2025

Why Temperature and Humidity Matter Many store holiday decorations in the garage or attic, but with temperature fluctuations and additional humidity, Ariz advises against it. —Gabi De La Rosa, Southern Living, 29 Nov. 2025

Paint Be careful because paint is highly sensitive to temperature fluctuations. —Mary Cornetta, Better Homes & Gardens, 29 Nov. 2025

Allavino 99-Bottle Wine Refrigerator More serious oenophiles can protect their precious collection with this refrigerator, that employs technology to reduce fluctuations in humidity and keep temperature steady. —Mark Marino, Bon Appetit Magazine, 28 Nov. 2025

Word History

First Known Use

15th century, in the meaning defined above

Rhymes for fluctuation

• abdication
• aberration
• abjuration
• abnegation
• abrogation
• acceptation
• acclamation
• acclimation
• accusation
• activation
• actuation
• acylation

Medical 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)

fluctuate

ˈflək-chə-ˌwāt 

verb

fluctuated; fluctuating