The Collaborative International Dictionary of English v.0.48:

Dissent \Dis*sent"\, n.
   1. The act of dissenting; difference of opinion; refusal to
      adopt something proposed; nonagreement, nonconcurrence, or
      disagreement.
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            The dissent of no small number [of peers] is
            frequently recorded.                  --Hallam.
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   2. (Eccl.) Separation from an established church, especially
      that of England; nonconformity.
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            It is the dissidence of dissent and the
            protestantism of the Protestant religion. --Burke.
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   3. Contrariety of nature; diversity in quality. [Obs.]
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            The dissent of the metals.            --Bacon.

   Syn: Disagreement; variance; difference; nonconcurrence;
        nonconformity.
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The Collaborative International Dictionary of English v.0.48:

Dissent \Dis*sent"\, v. i. [imp. & p. p. Dissented; p. pr. &
   vb. n. Dissenting.] [L. dissentire, dissentum; dis- +
   sentire to feel, think. See Sense.]
   1. To differ in opinion; to be of unlike or contrary
      sentiment; to disagree; -- followed by from.
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            The bill passed . . . without a dissenting voice.
                                                  --Hallam.
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            Opinions in which multitudes of men dissent from us.
                                                  --Addison.
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   2. (Eccl.) To differ from an established church in regard to
      doctrines, rites, or government.
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   3. To differ; to be of a contrary nature. --Hooker.
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WordNet (r) 3.0 (2006):

dissent
    n 1: (law) the difference of one judge's opinion from that of
         the majority; "he expressed his dissent in a contrary
         opinion"
    2: a difference of opinion
    3: the act of protesting; a public (often organized)
       manifestation of dissent [syn: protest, objection,
       dissent]
    v 1: withhold assent; "Several Republicans dissented" [ant:
         accede, acquiesce, assent]
    2: express opposition through action or words; "dissent to the
       laws of the country" [syn: protest, resist, dissent]
    3: be of different opinions; "I beg to differ!"; "She disagrees
       with her husband on many questions" [syn: disagree,
       differ, dissent, take issue] [ant: agree, concord,
       concur, hold]