where does the term xmas come from

The term "Xmas" is a shortened version of the word "Christmas". It is derived from the Greek word "Christos", which means "anointed one" or "messiah". The "X" in Xmas is a symbol used in ancient Greek to represent the Greek letter "Chi", which is the first letter in the Greek word "Christos". By using the letter "X" instead of the full word, it is a more compact and convenient way to refer to the holiday, and has been used since the Middle Ages.