dissent has 6 distinct synonyms spread across 3 of its 6 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is assent.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
(law) the difference of one judge's opinion from that of the majority
“he expressed his dissent in a contrary opinion”
the act of protesting; a public (often organized) manifestation of dissent
be of different opinions
“I beg to differ!”
Synonyms, antonyms and the broader and narrower relations for dissent come from Princeton University’s WordNet. Full sources and licences.