vacillate

/ˈvæ.sə.leɪt/

//ˈvæ.sə.leɪt// verb

By · According to Wiktionary data (CC BY-SA) ·

"vacillate" is a 9-letter English headword indexed on PlainSpell.

The verdict

“vacillate” is uncommon English (outside the top frequency list), classed as a verb. The kind of spelling people second-guess.

Unranked
below top-frequency English
9
letters

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - To sway unsteadily from one side to the other; oscillate.

Key facts for vacillate
PropertyValue
Headwordvacillate
LanguageEnglish
Part of speechVerb
IPA/ˈvæ.sə.leɪt/
Letters9
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Where “vacillate” sits in English frequency

vacillate falls outside the top-100,000 ranked English words, the long-tail zone of technical, archaic, or low-frequency vocabulary, exactly where readers second-guess spellings most.

Beyond rank #100,000. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

vacillate is uncommon English outside the top frequency list, classed as averb, transcribed /ˈvæ.sə.leɪt/. Rarity is why readers land here mid-draft. 2 senses are on record.

vacillate doesn't appear in our generated misspelling index, a sign its spelling follows regular English conventions. Our confusable-pair dataset has no match for it, since no other headword is close enough in sound or shape to pair with it.

Etymologically, the entry records: From Latin vacillātum, supine form of vacillō (“sway, waver”). The correct English form is vacillate, spelled V-A-C-I-L-L-A-T-E.

Definition

  1. 1
    To sway unsteadily from one side to the other; oscillate.
  2. 2
    To swing indecisively from one course of action or opinion to another.

Etymology

From Latin vacillātum, supine form of vacillō (“sway, waver”).

Synonyms

staggerblow hot and coldwaffle

This word in other languages

vacilar(Español)vaciller(Français)schwanken(Deutsch)vacilar(Português)

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "vacillate"?
"vacillate" is spelled V-A-C-I-L-L-A-T-E. The IPA pronunciation is /ˈvæ.sə.leɪt/.
What does "vacillate" mean?
As a verb, "vacillate" means: To sway unsteadily from one side to the other; oscillate.
How do you pronounce "vacillate"?
The IPA (International Phonetic Alphabet) transcription for "vacillate" is /ˈvæ.sə.leɪt/. Click the speaker icon on the pronunciation badge above to hear it spoken aloud where audio is available.
What is the origin of the word "vacillate"?
From Latin vacillātum, supine form of vacillō (“sway, waver”). See the full etymology section above for more details.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Using “vacillate”

The practical upshot for anyone who landed here from a spell-check.

  • The one correct English spelling is V-A-C-I-L-L-A-T-E - every other letter order is a misspelling in standard orthography.
  • Say it as /ˈvæ.sə.leɪt/ (IPA); tap the speaker on the pronunciation badge to hear it where audio exists.
  • Browse more English words and confusable pairs in the same reference. English words
Data Source

Wiktionary (via kaikki.org), licensed under CC BY-SA & GFDL. Word ordering uses an open word-frequency list; misspelling variants are generated by edit-distance from the correct headword.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list FrequencyWords open word-frequency list