Breadcrumb Home > Dictionary > Index F fifth dimension: Meaning and Definition of Find definitions for: fifth' dimen'sion Pronunciation: [key] — Math., Physics. Math.,Physics. a theoretical dimension beyond or in addition to a fourth dimension. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Fifth Commandment fifth estate 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: aspirant Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language