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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The Collaborative International Dictionary of English v.0.48:

Protest \Pro*test"\, v. t.
   1. To make a solemn declaration or affirmation of; to
      proclaim; to display; as, to protest one's loyalty.
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            I will protest your cowardice.        --Shak.
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   2. To call as a witness in affirming or denying, or to prove
      an affirmation; to appeal to.
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            Fiercely [they] opposed
            My journey strange, with clamorous uproar
            Protesting fate supreme.              --Milton.
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   To protest a bill or To protest a note (Law), to make a
      solemn written declaration, in due form, on behalf of the
      holder, against all parties liable for any loss or damage
      to be sustained by the nonacceptance or the nonpayment of
      the bill or note, as the case may be. This should be made
      by a notary public, whose seal it is the usual practice to
      affix. --Kent. --Story.
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The Collaborative International Dictionary of English v.0.48:

Protest \Pro"test\, n. [Cf. F. prot[^e]t, It. protesto. See
   Protest, v.]
   1. A solemn declaration of opinion, commonly a formal
      objection against some act; especially, a formal and
      solemn declaration, in writing, of dissent from the
      proceedings of a legislative body; as, the protest of
      lords in Parliament.
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   2. (Law)
      (a) A solemn declaration in writing, in due form, made by
          a notary public, usually under his notarial seal, on
          behalf of the holder of a bill or note, protesting
          against all parties liable for any loss or damage by
          the nonacceptance or nonpayment of the bill, or by the
          nonpayment of the note, as the case may be.
      (b) A declaration made by the master of a vessel before a
          notary, consul, or other authorized officer, upon his
          arrival in port after a disaster, stating the
          particulars of it, and showing that any damage or loss
          sustained was not owing to the fault of the vessel,
          her officers or crew, but to the perils of the sea,
          etc., ads the case may be, and protesting against
          them.
      (c) A declaration made by a party, before or while paying
          a tax, duty, or the like, demanded of him, which he
          deems illegal, denying the justice of the demand, and
          asserting his rights and claims, in order to show that
          the payment was not voluntary. --Story. --Kent.
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WordNet (r) 3.0 (2006):

protest
    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: the act of protesting; a public (often organized)
       manifestation of dissent [syn: protest, objection,
       dissent]
    3: the act of making a strong public expression of disagreement
       and disapproval; "he shouted his protests at the umpire"; "a
       shower of protest was heard from the rear of the hall"
    v 1: utter words of protest
    2: express opposition through action or words; "dissent to the
       laws of the country" [syn: protest, resist, dissent]
    3: affirm or avow formally or solemnly; "The suspect protested
       his innocence"