High Quality Content by WIKIPEDIA articles! "Xmas" is a common abbreviation of the word "Christmas". It is sometimes pronounced / ksm s/, but it, and variants such as "Xtemass", originated as handwriting abbreviations for the typical pronunciation, / kr sm s/. The "-mas" part is from the Latin-derived Old English word for "mass", while the "X" comes from the Greek letter Chi, which is the first letter of the Greek word , translated as "Christ".