1530s, from L. dissidentem (nom. dissidens), prp. of dissidere "to be remote, disagree, be removed from," lit. "to sit apart," from dis- "apart" + sedere "to sit" (see sedentary). The noun in the political sense first used 1940, with rise of totalitarian systems, especially with ref. to the Soviet Union. The noun is first recorded 1766, in allusion to Protestants.