definition of
vacillate

[1] #1 vacillate v. [hover, vibrate, oscillate] be undecided about something; waver between conflicting positions or courses of action; "He oscillates between accepting the new position and retirement". wn

[2] #2 vacillate v. [fluctuate, waver] move or sway in a rising and falling or wavelike pattern; "the line on the monitor vacillated". wn