/ Dictionary / Index Q quindecennial: Meaning and Definition of Find definitions for: quin•de•cen•ni•al Pronunciation: (kwin"di-sen'?-ul), [key] ? adj. of or pertaining to a period of 15 years or the 15th occurrence of a series, as an anniversary. ?n. a 15th anniversary. Random House Unabridged Dictionary, Copyright 1997, by Random House, Inc., on Infoplease. quindecagon quindecillion Related Content Daily Word Quiz: anecdote Analogy of the Day: Today?s Analogy Spelling Bee: Today?s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language