The day on which Christians celebrate the birth of Jesus Christ. Although the actual day of the year of the birth is not known, most Christians in the Western world celebrate the birth on December 25. The word Christmas comes from the early English phrase Christes Masse, which means Christ's Mass. The day is also commemorated as the Feast of the Nativity.
Source: A Dictionary for United Methodists, Alan K. Waltz, Copyright 1991, Abingdon Press. Used by Permission.