fluctuate

verb

fluc·​tu·​ate ˈflək-chə-ˌwāt 

-chü-ˌāt

fluctuated; fluctuating

intransitive verb

1

: to shift back and forth uncertainly

Oil prices fluctuated.

Temperatures fluctuated.

2

: to rise and fall in or as if in waves

The boat fluctuated on the rough sea.

transitive verb

: to cause to fluctuate

Synonyms

• vary
• change
• shift

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

The high costs associated with building and maintaining in-house data centers combined with fluctuating data needs allows colocation companies like Equinix to thrive. —Kenneth Squire, CNBC, 2 Aug. 2025

Jai Joon Lee, a professor of business management at Sacramento State, said the industry’s strife is not limited to the Sacramento region, with breweries across the country struggling with fluctuating consumer demand for craft beer. —Camila Pedrosa, Sacbee.com, 2 Aug. 2025

But the rules are changing, and a new wave of trade policies marked by fluctuating tariffs has introduced a level of uncertainty that’s hard to ignore. —Jennifer Wakefield, Forbes.com, 31 July 2025

While fresh information this week could prove significant, forecasters still face challenges posed by fluctuating tariffs and unforeseen shifts in the data, Jones said. —Max Zahn, ABC News, 30 July 2025

Word History

Etymology

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

Rhymes for fluctuate

• abdicate
• abrogate
• acetate
• activate
• actuate
• adsorbate
• aggravate
• agitate
• alginate
• alienate
• allocate
• amputate

Kids Definition

fluctuate

verb

fluc·​tu·​ate ˈflək-chə-ˌwāt 

fluctuated; fluctuating

1

: to move up and down or back and forth like a wave

2

: to be constantly changing especially up and down

fluctuation

ˌflək-chə-ˈwā-shən 

noun