To move back and forth or from side to side, as if about to fall
To be irresolute in acting or doing
To change one's attitudes or policies, for example
Guys might also vacillate between two extremes.
You can watch them vacillate all day long trying to decide whether to wear a red shirt or a blue one.
It will accompany you to the office or to the store, it will be held firmly in your hands as you vacillate over expensive electronic purchases.
Librans are well known for their ability to vacillate between two options, and this process of making up their mind can go on for quite some time.
They do not vacillate with regard to their task of considering whatever object appears.