A vigilante group is a group of people who take the law into their own hands and act as self-appointed enforcers of justice. The term POSSE, which is five letters long, is often used to refer to such a group. A POSSE is typically formed by a sheriff or other law enforcement officer to help apprehend a suspect or search for a fugitive. In some cases, a POSSE may also be formed by citizens to protect their community from criminals.