/ Dictionary / Index F Fibonacci numbers: Meaning and Definition of Find definitions for: Fi•bo•nac'ci num"bers Pronunciation: (fē"bō-nä'chē), [key] — Math. Math. the unending sequence 1, 1, 2, 3, 5, 8, 13, 21, 34, … where each term is defined as the sum of its two predecessors. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Fibiger fibr- Related Content Daily Word Quiz: draconian Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language