Vacillate means to waver back and forth, unable to decide. You might vacillate between ordering waffles and pancakes at your favorite diner — it’s hard to pick just one when both are so tasty!

Something that vacillates sways or fluctuates, often quite unsteadily. So use this verb to describe the staggering motions of a person who has had too much to drink, as well as the opinions of someone who can’t make up her mind. Synonyms include vibrate, hesitate, and waver. A wise Ethiopian proverb advises, "Do not vacillate or you will be left in between doing something, having something, and being nothing.”

Definitions of vacillate

v be undecided about something; waver between conflicting positions or courses of action

hover, oscillate, vibrate
be uncertain and vague
Type of:
hesitate, waffle, waver
pause or hold back in uncertainty or unwillingness

v move or sway in a rising and falling or wavelike pattern

“the line on the monitor vacillated
fluctuate, waver
cause to fluctuate or move in a wavelike pattern
Type of:
alternate dramatically between high and low values

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