The Collaborative International Dictionary of English v.0.48:

Vacillation \Vac`il*la"tion\, n. [L. vacillatio: cf. F.
   vacillation.]
   1. The act of vacillating; a moving one way and the other; a
      wavering.
      [1913 Webster]

            His vacillations, always exhibited most pitiably in
            emergencies.                          --Macaulay.
      [1913 Webster]

   2. Unsteadiness of purpose; changeableness.
      [1913 Webster]

            There is a vacillation, or an alternation of
            knowledge and doubt.                  --Jer. Taylor.
      [1913 Webster]

WordNet (r) 3.0 (2006):

vacillation
    n 1: indecision in speech or action [syn: hesitation,
         vacillation, wavering]
    2: changing location by moving back and forth [syn: swing,
       swinging, vacillation]