The term "Xmas" is a shortened form of the word "Christmas." It was first used in the 1500s as a way to abbreviate the word for convenience, and it has been used ever since. The "X" in "Xmas" stands for the Greek letter "chi," which is the first letter in the Greek word for Christ (Christos). So, "Xmas" is essentially a way to write "Christmas" without the "Christ" part. However, some people believe that using "Xmas" takes away from the religious meaning of Christmas and is disrespectful to the holiday.