Xmas is a common abbreviation of the word Christmas. It is sometimes pronounced /ˈɛksməs/, but Xmas, and variants such as Xtemass, originated as handwriting abbreviations for the typical pronunciation /ˈkrɪsməs/. The “X” comes from the Greek letter Chi, which is the first letter of the Greek word Χριστός, which in English is “Christ”. The “-mas” part is from the Latin-derived Old English word for Mass.
There is a common belief that the word Xmas stems from a secular attempt to remove the religious tradition from Christmas by taking the “Christ” out of “Christmas”, but its use dates back to the 16th century.
Ho ho ho ha HA HA!
Merry Xmas Happy Holidays*, y’all!