vacillate

verb

vac·​il·​late ˈva-sə-ˌlāt 

vacillated; vacillating

intransitive verb

1

: to waver in mind, will, or feeling : hesitate in choice of opinions or courses

2

a

: to sway through lack of equilibrium

b

: fluctuate, oscillate

vacillatingly

ˈva-sə-ˌlā-tiŋ-lē 

adverb

vacillator

ˈva-sə-ˌlā-tər 

noun

Synonyms of vacillate

• hesitate
• falter

Choose the Right Synonym for vacillate

hesitate, waver, vacillate, falter mean to show irresolution or uncertainty.

hesitate implies a pause before deciding or acting or choosing.

hesitated before answering the question

waver implies hesitation after seeming to decide and so connotes weakness or a retreat.

wavered in his support of the rebels

vacillate implies prolonged hesitation from inability to reach a firm decision.

vacillated until events were out of control

falter implies a wavering or stumbling and often connotes nervousness, lack of courage, or outright fear.

never once faltered during her testimony

Examples of vacillate in a Sentence

She has vacillated on this issue.

vacillated for so long that someone else stepped in and made the decision

Recent Examples on the Web

That has had a ripsaw effect on Musk, who is now vacillating between being the world’s first active trillionaire and the world’s first former-trillionaire. — Joe Wilkins, Futurism, 2 July 2026

The characters have little time to make life-or-death decisions, let alone ruminate, and the action vacillates between triage and doctors expertly improvising solutions — like Mel (Taylor Dearden) donating her own blood, and Javadi (Shabana Azeez) going MacGyver mode with a tracheal tube. — Ew Staff, Entertainment Weekly, 25 June 2026

Legally an adult but still a teenager and finding your footing in the world, vacillating between feeling invincible and feeling minuscule. — Bailey Johnson, Washington Post, 21 June 2026

Nanjiani seemed to vacillate between doing what past Taskmaster contestants have done or playing with authenticity, but both approaches left his identity on the show unclear. — Roxana Hadadi, Vulture, 17 June 2026

Word History

Etymology

borrowed from Latin vacillātus, past participle of vacillāre "to be unsteady, totter, be weak or inconstant, waver," of uncertain origin

First Known Use

1597, in the meaning defined at sense 2a

Rhymes for vacillate

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

Kids Definition

vacillate

verb

vac·​il·​late ˈvas-ə-ˌlāt 

vacillated; vacillating

: to hesitate between courses or opinions : be unable to choose

vacillation

ˌvas-ə-ˈlā-shən

noun

vacillator

ˈvas-ə-ˌlāt-ər 

noun