A separatist is someone who belongs to a group that wants to leave the country they are in and start a new country, with its own government. You can also put it before a noun: a separatist group, a separatist leader, a separatist war. It is a news-and-politics word, fairly formal, and it often comes from outside the group — newspapers and governments name people this way. The people themselves may say they are fighting for independence, or that they are patriots of their region. In older religious history, separatists were also people who left a national church to worship on their own; that sense still turns up in history books about England and early America. In an English class in Taiwan, the political sense is the one that matters.