The Collaborative International Dictionary of English v.0.48:

Tergiversation \Ter`gi*ver*sa"tion\, n. [L. tergiversario: cf.
   F. tergiversation.]
   1. The act of tergiversating; a shifting; shift; subterfuge;
      evasion.
      [1913 Webster]

            Writing is to be preferred before verbal
            conferences, as being freer from passions and
            tergiversations.                      --Abp.
                                                  Bramhall.
      [1913 Webster]

   2. Fickleness of conduct; inconstancy; change.
      [1913 Webster]

            The colonel, after all his tergiversations, lost his
            life in the king's service.           --Clarendon.
      [1913 Webster]

WordNet (r) 3.0 (2006):

tergiversation
    n 1: falsification by means of vague or ambiguous language [syn:
         equivocation, tergiversation]
    2: the act of abandoning a party for cause [syn: apostasy,
       tergiversation]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "tergiversation":
   about-face, amphibology, apostasy, denial, desertion, disavowal,
   double entendre, double meaning, equivocality, equivocation,
   equivoque, falseness, forswearing, recreancy, renunciation,
   repudiation, reversal, reverse