1940, in reference to heartbeat, from de- + fibrillation "a beating in an abnormal way," from Modern Latin fibrilla, diminutive of fibra "fiber," in reference to the muscle strands of the heart that contract irregularly in this condition.
defibrillation de·fib·ril·la·tion (dē-fĭb'rə-lā'shən, -fī'brə-)
n.
The stopping of fibrillation of the heart muscle and the restoration of normal contractions using of drugs or electric shock.