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

Example Sentences

She has vacillated on this issue. vacillated for so long that someone else stepped in and made the decision
Recent Examples on the Web In the months since, Pence has vacillated between defending his former running mate, speaking out against about Trump’s actions and opposing the former president by proxy in intra-party races. Seema Mehta, Los Angeles Times, 19 Apr. 2023 Kane’s paper reveals that after only some 3.5 million years, a super-earth inserted between the present orbits of mars and Jupiter would begin to vacillate wildly. Bruce Dorminey, Forbes, 21 Feb. 2023 Yes, the celebrity component causes the prank to vacillate between iconic and moronic faster than even the world’s best (worst) prankster, Winston Bishop, could manage. Vulture, 3 Apr. 2023 Between rising interest rates, failing banks, a crypto winter and a stock market that is vacillating between bullish and bearish on a seemingly daily basis, money is top of mind for almost everyone these days. Alex Weprin, The Hollywood Reporter, 22 Mar. 2023 Internal Fox messages revealed in court filings Tuesday as part of a defamation lawsuit against Fox by Dominion Voting Systems showed Carlson vacillating on his support for Trump after the 2020 election. Michael Scherer, Josh Dawsey And Sarah Ellison, Anchorage Daily News, 9 Mar. 2023 The location of this front may vacillate north and south; it is essentially caught in a tug-of-war between southwesterly winds rounding the Bermuda High over the Atlantic, and northeasterly flow associated with a cool dome of high pressure to our north. Ian Livingston, Washington Post, 8 July 2022 The flooding, which follows several years of extreme drought, showcases the weather whiplash typical of California, which vacillates between too wet and too dry. Evan Bush, NBC News, 2 Apr. 2023 It's had a history in Wisconsin, that is it's vacillated from time to time, which is basically caps recoveries in particular situations. Drew Dawson, Journal Sentinel, 31 Mar. 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 8 Jun. 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

More from Merriam-Webster on vacillate

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