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

• 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

One of those unique risk factors is thought to be the hormone fluctuations of menopause, leading researchers to study whether hormone replacement therapy (HRT), which can level the hormonal playing field, might help. —Erica Sloan, SELF, 15 Sep. 2025

The data didn’t lie — scientists identified physiological patterns that aligned with the fluctuation of key pregnancy hormones such as estrogen, progesterone, and human chorionic gonadotropin (hCG). —Maria Mocerino, Interesting Engineering, 13 Sep. 2025

These fluctuations are normal and largely directed by your circadian rhythm (the body's internal clock). —Md Published, Verywell Health, 13 Sep. 2025

Primordial black holes are theorized to have been created not from stars but as a result of initial density fluctuations in the universe moments after the Big Bang. —Robert Lea, Space.com, 12 Sep. 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