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Medical Term:


Pronunciation: fī-bri-lā′shŭn, fib-rĭ-


  1. The condition of being fibrillated.
  2. The formation of fibrils.
  3. Exceedingly rapid contractions or twitching of muscular fibrils, but not of the muscle as a whole.
  4. Vermicular twitching, usually slow, of individual muscular fibers; commonly occurs in atria or ventricles of the heart as well as in recently denervated skeletal muscle fibers.