defector (n.)

"a seceder or deserter," 1660s, agent noun in Latin form from defect, or else from Latin defector "revolter," agent noun from deficere "to desert, revolt, fail," from de "down, away" (see de-) + combining form of facere "to do, make" (from PIE root *dhe- "to set, put"). Specifically of important persons who fled the Soviet-dominated countries to the West by 1953.