dissident

Short definition from Wiktionary

Adjective

1. 1
   In a manner that disagrees; dissenting; discordant.
2. 2
   Continuing violent actions despite a ceasefire (especially the Good Friday Agreement).

Noun

1. 1
   A person who formally opposes the current political structure, the political group in power, the policies of the political group in power, or current laws.
2. 2
   One who disagrees or dissents; one who separates from the established religion.
3. 3
   One who disagrees or dissents; one who separates from the established religion: Sometimes Dissident: in the kingdom of Poland, the name for Christians not part of the Roman Catholic Church.