The Collaborative International Dictionary of English v.0.48:

Protestation \Prot`es*ta"tion\, n. [L. protestatio: cf. F.
   protestation. See Protest.]
   1. The act of making a protest; a public avowal; a solemn
      declaration, especially of dissent. " The protestation of
      our faith." --Latimer.
      [1913 Webster]

   2. (Law) Formerly, a declaration in common-law pleading, by
      which the party interposes an oblique allegation or denial
      of some fact, protesting that it does or does not exist,
      and at the same time avoiding a direct affirmation or
      denial.
      [1913 Webster]

WordNet (r) 3.0 (2006):

protestation
    n 1: a formal and solemn declaration of objection; "they
         finished the game under protest to the league president";
         "the senator rose to register his protest"; "the many
         protestations did not stay the execution" [syn: protest,
         protestation]
    2: a strong declaration of protest