Definition of "Rebel" :

noun: a person who takes part in an armed rebellion against the constituted authority (especially in the hope of improving conditions)

noun: someone who exhibits great independence in thought and action

noun: Johnny' was applied as a nickname for Confederate soldiers by the Federal soldiers in the American Civil War; greyback' derived from their grey Confederate uniforms

verb: take part in a rebellion; renounce a former allegiance

verb: break with established customs