fluc·​tu·​ate ˈflək-chə-ˌwāt How to pronounce fluctuate (audio)
fluctuated; fluctuating

intransitive verb

: to shift back and forth uncertainly
Oil prices fluctuated.
Temperatures fluctuated.
: to rise and fall in or as if in waves
The boat fluctuated on the rough sea.

transitive verb

: to cause to fluctuate
Choose the Right Synonym for fluctuate

swing, sway, oscillate, vibrate, fluctuate, waver, undulate mean to move from one direction to its opposite.

swing implies a movement of something attached at one end or one side.

the door suddenly swung open

sway implies a slow swinging or teetering movement.

trees swaying in the breeze

oscillate stresses a usually regular alternation of direction.

an oscillating fan

vibrate suggests the rapid oscillation of an elastic body under stress or impact.

the vibrating strings of a piano

fluctuate suggests constant irregular changes of level, intensity, or value.

fluctuating interest rates

waver stresses irregular motion suggestive of reeling or tottering.

the exhausted runner wavered before collapsing

undulate suggests a gentle wavelike motion.

an undulating sea of grass

Examples of fluctuate in a Sentence

His popularity has fluctuated during his term in office. In the desert, the temperature fluctuates dramatically.
Recent Examples on the Web Despite everything, Kharkiv remains home to one of Ukraine’s most vibrant Jewish communities — about 25,000 people in all before the invasion, a number that has fluctuated, halved at times, as refugees have fled and again returned home. Laura King, Los Angeles Times, 17 Sep. 2023 Priceline referenced data from Sept. 1-13 as the booking period, so prices may fluctuate. Evie Carrick, Travel + Leisure, 15 Sep. 2023 That means prices don’t fluctuate much from seller to seller. Laura Daily, Washington Post, 11 Sep. 2023 The powerful storm, which has fluctuated in intensity throughout its time over the open Atlantic, is expected to become a very dangerous Category 4 by late Sunday or early Monday morning, according to the National Hurricane Center. Taylor Ward, CNN, 10 Sep. 2023 Missing tallies have fluctuated drastically since the deadly August blaze; the initial number was over 3,000, then 385, and now, based on calls and emails the FBI has received, is 66. Cara Tabachnick, CBS News, 9 Sep. 2023 Feed your gut The all-important gut can also be affected by fluctuating levels of oestrogen. Georgia Day, Vogue, 6 Sep. 2023 Research suggests that dreaming brains still register the erratic heart rate, variable breathing, and fluctuating blood pressure that are typical during REM sleep. Amanda Gefter, The New Yorker, 31 Aug. 2023 But even that could get boring for grade-school students with fluctuating attention spans. Adam Himmelsbach, BostonGlobe.com, 30 Aug. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'fluctuate.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Latin fluctuatus, past participle of fluctuare, from fluctus flow, wave, from fluere — more at fluid

First Known Use

1604, in the meaning defined at intransitive sense 2

Time Traveler
The first known use of fluctuate was in 1604

Dictionary Entries Near fluctuate

Cite this Entry

“Fluctuate.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/fluctuate. Accessed 27 Sep. 2023.

Kids Definition


fluc·​tu·​ate ˈflək-chə-ˌwāt How to pronounce fluctuate (audio)
fluctuated; fluctuating
: to move up and down or back and forth like a wave
: to be constantly changing especially up and down
fluctuation noun

More from Merriam-Webster on fluctuate

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