Breadcrumb Home > Dictionary Cite Meaning of Twelfth Day Find definitions for: Twelfth' Day' Pronunciation: [key] the 12th day after Christmas, January 6, on which the festival of the Epiphany is celebrated: formerly observed as the last day of the Christmas festivities. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Twelfth Amendment Twelfth Night Related Content Daily Word Quiz: persiflage Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language