Source : Webster's Revised Unabridged Dictionary (1913)

Vacillant \Vac"il*lant\, a. [L. vacillans, p. pr. of vacillare:
   cf. F. vacillant. See {Vacillate}.]
   Vacillating; wavering; fluctuating; irresolute.

Source : WordNet®

vacillant
     adj : uncertain in purpose or action [syn: {vacillating}, {wavering}]