secessionist (plural secessionists)
- A person who secedes or supports secession from a political union or an alliance or organisation.
- Gustav Klimt was of the Viennese secessionist school.
A common usage is for supporters of the Confederacy during the United States Civil War.
As well as being applied to people and movements, 'secessionist' is commonly used to describe opinions or beliefs and the form of their expression in books, articles, or speeches.