The X in Christmas is a Greek letter that represents the word "Christ" in Greek, which is the root of the word "Christmas." The X stands for Christ as the central figure of the holiday. The X is also used as a symbol of the cross, which is an important symbol in Christianity. It is also commonly used as a symbol of the season, representing the star that guided the wise men to the birth of Jesus. The X has a deep meaning and significance in the celebration of Christmas.