Christmas, annual Christian holiday commemorating the birth of Jesus Christ. Most members of the Roman Catholic Church and followers of Protestantism celebrate Christmas on December 25, and many celebrate on the evening of December 24 as well. Members of the Eastern Orthodox Church usually delay their most important seasonal ceremonies until January 6, when they celebrate Epiphany, a commemoration of the baptism of Jesus. Epiphany also traditionally commemorates the arrival of the Three Wise Men of the East in Bethlehem (near Jerusalem, Israel), where they adored the infant Jesus and presented him with gifts of gold, frankincense, and myrrh. The official Christmas season, popularly known as either Christmastide or the Twelve Days of Christmas, extends from the anniversary of Christ’s birth on December 25 to the feast of Epiphany on January 6. Christmas is based on the story of Jesus’ birth as described in the Gospel according to Matthew (see Matthew 1:18-2:12) and the Gospel according to Luke (see Luke 1:26-56). Roman Catholics first celebrated Christmas, then known as the Feast of the Nativity, as early as 336 ad. The word Christmas entered the English language sometime around 1050 as the Old English phrase Christes maesse, meaning “festival of Christ.” Scholars believe the frequently used shortened form of Christmas—Xmas—may have come into use in the 13th century. The X stands for the Greek letter chi, an abbreviation of Khristos (Christ), and also represents the cross on which Jesus was crucified.