- A person involved in armed conflict against an occupation, or oppressive government, etc.; a revolutionary, an insurgent, a rebel or insurrectionist.
Usage notes 
The same person can be called a terrorist, especially by the oppressor. At the same time, a terrorist by all means can be called freedom fighter in propaganda depending on one's ideologies (e.g. the Contra rebels that fought against the Marxist Sandinista leadership in Nicaragua were labeled freedom fighters by Ronald Reagan).