vacillate
Concise Oxford English Dictionary © 2008 Oxford University Press:
vacillate /ˈvasɪleɪt/
▶verb waver between different opinions or actions.
– derivatives
vacillation noun,
vacillator noun.
vacillation noun,
vacillator noun.
– origin C16 (earlier (ME) as vacillation), in the sense ‘sway unsteadily’: from L. vacillat-, vacillare ‘sway’.
'vacillate' also found in these Oxford entries:

