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 But organizations always vacillate between factoring in cost, ease of use, and risk. Lily Hay Newman, WIRED, 17 Feb. 2023 That’s the keep-you-guessing appeal of Deep Water, which sees Vic and Melinda’s relationship vacillate between tenderness and simmering rage. David Sims, The Atlantic, 16 Mar. 2022 Lucy’s perceptions of her first husband vacillate in maddeningly recognizable ways. Washington Post, 19 Oct. 2021 Job candidates often feel awkward when talking about their skills and vacillate between being too aggressive or bland when interviewing. Kim Thompson, Chron, 21 Aug. 2021 Then there will be players who vacillate about the vaccine, guys like Tampa Bay’s Leonard Fournette. Bill Plaschke, Los Angeles Times, 26 July 2021 In pieces like p1eta™️, Chapin tries to reconcile the polarity that women vacillate between — Eve as wicked and full of knowledge, the Virgin Mary as pure and worthy. Brienne Walsh, Forbes, 26 Apr. 2021 Some dedicate half or whole days to each of their primary processes, but the key is to not vacillate back-and-forth between them. Tim Maurer, Forbes, 11 Apr. 2021 Many South Korean voters vacillate between the two major parties and tend to make up their minds just weeks before presidential votes. Andrew Jeong, WSJ, 7 Apr. 2021 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'vacillate.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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 22 Mar. 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

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Challenging Standardized Test Words

  • high school student holding a pencil leaning over a sat test
  • Despite the cacophony, the student tried to study.
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!

Solve today's spelling word game by finding as many words as you can with using just 7 letters. Longer words score more points.

Can you make 12 words with 7 letters?