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.
      [1913 Webster]

            The bill passed . . . without a dissenting voice.
                                                  --Hallam.
      [1913 Webster]

            Opinions in which multitudes of men dissent from us.
                                                  --Addison.
      [1913 Webster]

   2. (Eccl.) To differ from an established church in regard to
      doctrines, rites, or government.
      [1913 Webster]

   3. To differ; to be of a contrary nature. --Hooker.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

dissenting \dissenting\ adj.
   disagreeing, especially with a majority.

   Syn: dissentient, dissident.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

dissenting
    adj 1: disagreeing, especially with a majority [syn:
           dissentient, dissenting(a), dissident]