The Collaborative International Dictionary of English v.0.48:

Protest \Pro*test"\, v. i. [imp. & p. p. Protested; p. pr. &
   vb. n. Protesting.] [F. protester, L. protestari, pro
   before + testari to be a witness, testis a witness. See
   Testify.]
   1. To affirm in a public or formal manner; to bear witness;
      to declare solemnly; to avow.
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            He protest that his measures are pacific. --Landor.
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            The lady doth protest too much, methinks. --Shak.
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   2. To make a solemn declaration (often a written one)
      expressive of opposition; -- with against; as, he protest
      against your votes. --Denham.
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            The conscience has power . . . to protest againts
            the exorbitancies of the passions.    --Shak.
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   Syn: To affirm; asseverate; assert; aver; attest; testify;
        declare; profess. See Affirm.
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Moby Thesaurus II by Grady Ward, 1.0:

33 Moby Thesaurus words for "protesting":
   complaining, disputatious, disputing, dissentient, dissenting,
   expostulative, expostulatory, fractious, noncooperative, objecting,
   obstructive, on the barricades, proof against, protestant,
   rebellious, recalcitrant, refractory, reluctant, remonstrant,
   remonstrative, renitent, repellent, resistant, resisting,
   resistive, retardant, retardative, uncooperative, under protest,
   unsubmissive, unyielding, up in arms, withstanding