Breadcrumb Home > Dictionary > Index D decennium: Meaning and Definition of Find definitions for: de•cen•ni•um Pronunciation: (di-sen'ē-um), [key] — pl. -cen•ni•ums, -cen•ni•a a period of ten years; a decade. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: decennium (Thesaurus) decennial decent TrendingHere are the facts and trivia that people are buzzing about. Jewish Holidays, 2010-2030 (A.M. 5770-5791) Western Christian Holidays, 2010-2030 12 Steps to a New Year New Year's Resolution to Slim Down? Martin Luther King Speeches Books of the Bible: Old Testament Books in Order ✖ Related Content Daily Word Quiz: spurious Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language