An insurgent is someone who actively fights against their own government or the people in power, usually through armed rebellion or organized resistance. The word describes people who rise up from within a country to challenge its established authority.

Insurgents are different from foreign invaders: they're part of the population they're fighting against. During the American Revolution, British authorities considered the colonial fighters to be insurgents rebelling against the Crown. When a group of citizens takes up arms against their government, they become an insurgency.

That uprising quality defines what insurgents do: they surge upward against existing power structures. Whether history remembers insurgents as heroes or villains often depends on whether their cause succeeds and who's telling the story. The American Founders were insurgents against British rule, but they became the established government after winning independence.

As an adjective, insurgent can also describe someone who challenges established leaders within an organization or political party, even without violence. A politician who runs against party leadership might be called an insurgent candidate. The word carries a sense of disruption and challenge to the status quo, whether that challenge involves weapons or just ideas that threaten existing power.