Dissidence is a kind of opposition or disagreement that's often aimed at a government. Sometimes dissidence takes the form of massive numbers of protesters marching in the streets.
The noun dissidence first appeared in the 17th century, defined as "separation in opinion." It comes from the Latin dissidere, "to disagree" or "to sit apart," and its roots, dis-, "apart," and sedere, "to sit." Dissidence occurs when a person (or a group) expresses strong objections to the policies or opinions of an official body. Dissidence can take various forms, from strikes and protests to newspaper editorials.