Rebels are people who are fighting against their own country's army in order to change the political system there.

Politicians who oppose some of their own party's policies can be referred to as rebels.

If politicians rebel against one of their own party's policies, they show that they oppose it.

You can say that someone is a rebel if you think that they behave differently from other people and have rejected the values of society or of their parents.

When someone rebels, they start to behave differently from other people and reject the values of society or of their parents.