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 of fluctuate

• 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

Your principal and interest payment won't change, although your total monthly payment can still fluctuate as property taxes and homeowners insurance costs change. — Rebecca Safier, USA Today, 26 Aug. 2026

Since the cash creators earn from views on platforms like TikTok, YouTube, and Facebook can fluctuate, affiliate links offer more consistent income. — Ct Jones, Rolling Stone, 25 Aug. 2026

Brent’s price fluctuated between $72 and $102 last month on halting talks between the United States and Iran. — ABC News, 25 Aug. 2026

That said, all of these interest earnings are approximate as rates can and will fluctuate, especially if the Federal Reserve issues rate hikes or cuts while the account is open. — Matt Richardson, CBS News, 25 Aug. 2026

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

• abate
• airfreight
• await
• baseplate
• berate
• birthdate
• birthrate
• bookplate
• borate
• breastplate
• bromate
• casemate

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