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

During flight, onboard electronics had to feed power continuously to twin electric motors while balancing the fluctuating harvest coming in from the solar array. — Aman Tripathi, Interesting Engineering, 30 Sep. 2026

Since then, the results have fluctuated between middling and downright putrid, and entering this year, Aranda was said to be on his last leg. — Austin Perry Outkick, FOXNews.com, 29 Sep. 2026

An active Pacific region Hurricane Polo has been a powerful storm, at times fluctuating between Category 4 and Category 5. — Kerry Breen, CBS News, 29 Sep. 2026

Suicide rates in the United States generally steadily rose from 2000 to 2018, and have fluctuated and slightly declined since then according to the US Centers for Disease Control and Prevention. — Kristen Rogers, CNN Money, 28 Sep. 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