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

That fluctuation of hormones causes this whole litany of symptoms, like hot flashes, night sweats, brain fog, joint pain, dry skin, brittle hair, hair loss, so many things. —Tribune News Service, Baltimore Sun, 2 Mar. 2026

Those kinds of scoring fluctuations won’t cut it — especially if the defense is inconsistent, too — for a player the Knicks acquired by trading five first-round picks in an outright haul for the Nets. —Kristian Winfield, Hartford Courant, 1 Mar. 2026

Liquid detergents are especially sensitive to temperature fluctuations, but all detergent types benefit from being stored at a stable temperature. —Jolie Kerr, Better Homes & Gardens, 27 Feb. 2026

The fluctuations hint at an episodic, external source—potentially eruptions from a sort of super-Io satellite being tidally squeezed by its hefty planetary host. —Phil Plait, Scientific American, 27 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