shillyshally vs vacillate

shillyshally is a noun but vacillate is not a noun.

Word	Noun	Adjective	Verb	Adverb
shillyshally	Yes	No	Yes	No
vacillate	No	No	Yes	No

As verbs, vacillate is a hypernym of shillyshally; that is, vacillate is a word with a broader meaning than shillyshally:

shillyshally: be uncertain and vague
vacillate: be undecided about something; waver between conflicting positions or courses of action

Other hypernyms of shillyshally include hover, oscillate, vibrate.

shillyshally (noun)	vacillate (noun)
the act of procrastinating; putting off or delaying or deferring an action to a later time

shillyshally (verb)	vacillate (verb)
be uncertain and vague	move or sway in a rising and falling or wavelike pattern
postpone doing what one should be doing	be undecided about something; waver between conflicting positions or courses of action