Xmas (also X-mas) is a common abbreviation of the word Christmas. It is sometimes pronounced , but Xmas, and variants such as Xtemass, originated as handwriting abbreviations for the typical pronunciation . The 'X' comes from the Greek letter Chi, which is the first letter of the Greek word Christós (Greek: Χριστός, translit. Khristós, lit. "anointed, covered in oil"), which became Christ in English. The suffix -mas is from the Latin-derived Old English word for Mass.

There is a common misconception that the word Xmas stems from a secularizing tendency to de-emphasize the religious tradition from Christmas, by "taking the Christ out of Christmas"; nevertheless, the term's usage dates back to the 16th century, and corresponds to Roman Catholic, Eastern Orthodox, Church of England, and Episcopalian liturgical use of various forms of chi-rho monogram. In English, "X" was first used as a scribal abbreviation for "Christ" in 1100; "X'temmas" is attested in 1551, and "Xmas" in 1721.