noun

a person who opposes official policy, especially that of an authoritarian state.

a dissident who had been jailed by a military regime

dissenter,objector,protester,disputant,freethinker,nonconformist,independent thinker,rebel,revolutionary,recusant,renegade,subversive,agitator,insurgent,insurrectionist,insurrectionary,disruptor,mutineer,refusenik

adjective

in opposition to official policy.

the measure was supported by dissident Tories

dissentient,dissenting,disagreeing,opposing,opposed,opposition,objecting,protesting,complaining,rebellious,rebelling,revolutionary,recusant,nonconformist,non-compliant