The Collaborative International Dictionary of English v.0.48:
Vacillant \Vac"il*lant\, a. [L. vacillans, p. pr. of vacillare: cf. F. vacillant. See Vacillate.] Vacillating; wavering; fluctuating; irresolute. [1913 Webster]WordNet (r) 3.0 (2006):
vacillant adj 1: uncertain in purpose or action [syn: vacillant, vacillating, wavering]