vac·​il·​late ˈva-sə-ˌlāt How to pronounce vacillate (audio)
vacillated; vacillating

intransitive verb

: to waver in mind, will, or feeling : hesitate in choice of opinions or courses
: to sway through lack of equilibrium
vacillatingly adverb
vacillator noun
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 The Met Gala theme often vacillates between straightforward retrospectives (such as the event’s 1996 homage to Christian Dior, and the 1997 theme dedicated to Gianni Versace) and more artful, subjective prompts. Leah Dolan, CNN, 15 Feb. 2024 In earlier cases, the court has vacillated on how much deference is enough; individual justices have also gone back and forth. Clive Crook, Twin Cities, 10 Feb. 2024 Egypt since 2011 has vacillated between the Muslim Brotherhood and military dictatorship, all the while beset by a festering economic crisis. Seth Cropsey, National Review, 10 Feb. 2024 Russians have always vacillated between wanting to be included and fearing contamination or corruption, from harboring an inferiority complex to delusions of grandeur. Elettra Pauletto, Harper's Magazine, 11 Dec. 2023 The reason the characters’ arias of vacillating conviction and doubt don’t ultimately break through our sternums—despite the actors’ emotional chops—is that there’s no real vulnerability on display in the writing. Sara Holdren, Vulture, 30 Nov. 2023 But one of the more useful signals in a forecaster's arsenal is the El Niño–Southern Oscillation in the tropical Pacific Ocean, which vacillates between warmer sea surface temperatures (El Niño), cooler ones (La Niña), and neutral conditions. Eric Berger, Ars Technica, 23 Oct. 2023 The Taliban authorities vacillated between grudging accommodation and weary rejection of our attention, but Ross had an uncanny ability to connect. Victor Blue, The New Yorker, 21 Dec. 2023 Susanna Vogel capably directs every sequence, though the movie vacillates between thriller and comedy in a way that doesn’t quite land. Elizabeth Logan, Glamour, 9 Oct. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'vacillate.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


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

Time Traveler
The first known use of vacillate was in 1597

Dictionary Entries Near vacillate

Cite this Entry

“Vacillate.” Dictionary, Merriam-Webster, Accessed 24 Feb. 2024.

Kids Definition


vac·​il·​late ˈvas-ə-ˌl(amacr}t How to pronounce vacillate (audio)
vacillated; vacillating
: to hesitate between courses or opinions : be unable to choose
vacillator noun

More from Merriam-Webster on vacillate

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