ˌfibrəˈlāshən, ˌfīb- noun
( -s )
1. : the act or process of forming fibrils or the state of being fibrillate
2.
a. : muscular twitching involving individual muscle fibers acting without coordination — compare fasciculation
b. : very rapid irregular contractions of the muscle fibers of the heart resulting in a lack of synchronism between heartbeat and pulse beat — see auricular fibrillation , ventricular fibrillation
3. : the breaking down of fibers such as occurs in beating paper pulp