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

Quince Lightweight Down Packable Puffer Hooded Jacket A packable puffer is an absolute non-negotiable for unexpected cold snaps and shoulder season weather fluctuations. —Jacqueline Dole, Travel + Leisure, 23 Feb. 2026

When liquid calories become your primary source of nutrition, your body experiences reduced satiety responses, unhealthy blood sugar fluctuations, and a higher risk of type 2 diabetes. —Anna Giorgi, Verywell Health, 23 Feb. 2026

Borrowed from the brand’s Reference Jubilee model, the DC AiR motor and flat belt work in concert with Clearaudio’s Tacho-Speed-Control (TSC) system, which continuously monitors rotational speed and adjusts for subtle variables such as stylus drag, belt fluctuations, and even temperature shifts. —Robert Ross, Robb Report, 22 Feb. 2026

For stone sinks, be sure to keep the water temperature similar to what the temperature of your kitchen is so that there isn't a significant fluctuation—that's when cracks start to form. —Shagun Khare, The Spruce, 21 Feb. 2026

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