not resolute; wavering; indecisive; hesitating: an ineffectual, vacillating person.
oscillating; swaying; fluctuating: a vacillating indicator.

Also vacillant.

Origin of vacillating

First recorded in 1805–15; vacillate + -ing2
Related formsvac·il·lat·ing·ly, adverbnon·vac·il·lat·ing, adjectiveun·vac·il·lat·ing, adjective

Synonyms for vacillating

1. See fickle.



verb (used without object), vac·il·lat·ed, vac·il·lat·ing.

to waver in mind or opinion; be indecisive or irresolute: His tendency to vacillate makes him a poor leader.
to sway unsteadily; waver; totter; stagger.
to oscillate or fluctuate.

Origin of vacillate

1590–1600; < Latin vacillātus (past participle of vacillāre to sway to and fro); see -ate1
Related formsvac·il·la·tor, noun

Synonyms for vacillate

1. hesitate. See waver1. 2. reel. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for vacillating

Contemporary Examples of vacillating

Historical Examples of vacillating

British Dictionary definitions for vacillating


rarely vacillant (ˈvæsɪlənt)


inclined to waver; indecisive
Derived Formsvacillatingly, adverb


verb (intr)

to fluctuate in one's opinions; be indecisive
to sway from side to side physically; totter or waver
Derived Formsvacillation, nounvacillator, noun

Word Origin for vacillate

C16: from Latin vacillāre to sway, of obscure origin
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for vacillating



1590s, "to sway unsteadily," from Latin vacillatum, from vacillare (see vacillation). Meaning "to waver between two opinions or courses" is recorded from 1620s. Related: Vacillated; vacillates; vacillating.

Online Etymology Dictionary, © 2010 Douglas Harper