The word “Christ” is easy to pick out. That is why we see so many people using the first part of this word to remind us to “keep CHRIST in Christmas.” The suffix “mas” may not be so simple. To some it simply means festival. So the word would mean “Christ’s Festival” referring either to the day or the season.
However that is not the origin of the word. Before 1150 Middle English the word would have been spelled in this fashion: cristmasse; in Old English Cristes mǣsse. Literally this means “Christ’s Mass Day” or the day on which one celebrates Mass to commemorate the Nativity of Jesus. Other similar words survive to this day. Candlemas Day is the day we bring candles to church in order to have them blessed. Michaelmas Day is the day on which we celebrate Mass calling to mind Saint Michael.
The Catholicity of this word is ancient and few people realize that they are wishing people a happy day on which we celebrate at Mass the birth of Jesus.
MERRY CHRISTMAS TO YOU!