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
  1. verb
    be undecided about something; waver between conflicting positions or courses of action
    synonyms: hover, oscillate, vibrate
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    be uncertain and vague
    type of:
    hesitate, waffle, waver
    pause or hold back in uncertainty or unwillingness
  2. verb
    move or sway in a rising and falling or wavelike pattern
    “the line on the monitor vacillated
    synonyms: fluctuate, waver
    cause to fluctuate or move in a wavelike pattern
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    type of:
    alternate dramatically between high and low values
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