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 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 But on Thursday, House Republicans vacillated on whether a third House speaker vote would be to their taste. Geoffrey Skelley, ABC News, 19 Oct. 2023 Recommended Responsibility From Florida to California, dwindling insurance options In recent weeks, his mother, has vacillated between elation and worry, especially fretting over her son’s ability to keep pace with his classmates. Bobby Caina Calvan, Robert Bumsted and Elliot Spagat , The Christian Science Monitor, 8 Sep. 2023 In recent weeks, his mother, 22, has vacillated between elation and worry, especially fretting over her son’s ability to keep pace with his classmates. Bobby Caina, Robert Bumsted and Elliot Spagat, Anchorage Daily News, 7 Sep. 2023 Not surprisingly, being the center of such wildly vacillating public opinion took its toll. Mary McNamara, Los Angeles Times, 12 Oct. 2023 Tweedy vacillates between inscrutable turns of phrase and heartfelt declarations of love and solidarity, but for the most part, there’s very little sugar-coating going on here. Jonathan Cohen, Spin, 27 Sep. 2023 In the decades that followed, how the military treated reports of subsequent sightings was in large part a function of Brazil’s own vacillating commitment to transparency. Terrence McCoy, Washington Post, 6 Sep. 2023 While the speaker has vacillated on Ukraine, McConnell has emerged as McCain’s political heir. Paul Kane, Washington Post, 2 Sep. 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 9 Dec. 2023.

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

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