Breadcrumb Home > Dictionary > Index F Cite fibrillation: Meaning and Definition of Find definitions for: fi•bril•la•tion Pronunciation: (fī"bru-lā'shun, or, esp. for 2, fib"ru-), [key] — n. the formation of fibrils. uncontrolled twitching or quivering of muscular fibrils. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: fibrillation (Thesaurus) fibrillate fibrilliform TrendingHere are the facts and trivia that people are buzzing about. January 2021 Current Events: US News The Holocaust (1933–1945) Chinese New Year History, Meaning, and Celebrations Noble Titles and Ranks in a Monarchy The 5 Best Air Purifiers of 2020 Inaugural Trivia Related Content Daily Word Quiz: obviate Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language