X-mas

X-mas and Xmas is an ancient abbreviation in Christian manuscripts using the Greek letter chi Χ χ for Christos ΧΡΙΣΤΟΣ Χρίστος. The suffix "-mas" from the Latin means Mass, the term itself originating in the Latin dismissal at the end of Catholic worship, Ite missa est "Go [forth in mission] it is [completed]", ultimately deriving its origin from the word of Christ commanding the Great Commission to "Go" forth with the divinely authorized "mission", both publicly to announce and proclaim Christ as Lord and Savior and Son of God, and personally by witnessing to Him daily "in your thoughts, words, and deeds".

Because the celebration of the Nativity of the Lord Jesus Christ was held to be, like Easter, one of the highest celebrations of orthodox catholic Christianity, it came to be revered as the Mass of Christ Himself, the "Christ-Mass", now Christmas and Xmas.