From Longman Dictionary of Contemporary Englishsecessionistse‧ces‧sion‧ist /sɪˈseʃənɪst/ noun [countable] someone who wants their country or state to be independent of another country
Examples from the Corpus
secessionist• On the one side are democrats, economic reformers and secessionists.• Assam, in common with other north-eastern states, had long been troubled by secessionist groups.• He calmed secessionist sentiment by dealing constructively with the regional parties of Kashmir, Assam and Punjab.• The main secessionist conflicts are in Punjab, Jammu & Kashmir, Assam and the north-eastern states. 