Open defiance and opposition, sometimes armed, to a person or thing in authority.
Example:
The substitute teacher attempted to end the student rebellion by insisting on absolute quiet.
These days, some degree of rebellion against parents and other authority figures is viewed as a normal part of growing up, as long as it is not destructive and does not go on too long. Rebellion, armed or otherwise, has often served to alert those in power to the discontent of those they control. The American War of Independence was first viewed by the British as a minor rebellion that would soon run its course.