Definitions of dissent:

• noun:   a difference of opinion
• noun:   (law) the difference of one judge's opinion from that of the majority

  Example: "He expressed his dissent in a contrary opinion"

• noun:   the act of protesting; a public (often organized) manifestation of dissent
• verb:   withhold assent

  Example: "Several Republicans dissented"

• verb:   express opposition through action or words

  Example: "Dissent to the laws of the country"

• verb:   be of different opinions