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

The site also shows live pricing that may fluctuate with the spot price of metals. — Jamela Adam, USA Today, 1 July 2026

Jeffreys noted that multiple sclerosis can fluctuate, with some patients able to work full time, some able to work flexibly and others unable to work at all. — Michelle Mbekeani, Forbes.com, 1 July 2026

Until this past Supreme Court term, emergency applications fluctuated year to year but showed no clear upward trend. — Ken B. Morales, ProPublica, 1 July 2026

But experts cautioned against reading too much into year-over-year numbers that can fluctuate based on many factors — including how authorities classify and count certain offenses. — Jazmin Alvarado, Los Angeles Times, 3 July 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