xmas
n. C / Un. a shorter way to write or say Christmas. You often see this on signs or in casual messages.
n. an informal abbreviation for Christmas. The 'X' represents the Greek letter 'chi', which is the first letter of 'Christ' in Greek.
We are going to visit my parents this Xmas.
The shop window was decorated with bright lights and a sign wishing everyone a merry Xmas.
While some purists dislike the abbreviation, Xmas has been used in written English for centuries as a convenient shorthand in both commercial and personal correspondence.
Attested in this form since 1755, and preceded by earlier forms such as X'temmas (1551) and Old English Χp̃es mæssa (1100), from Cristes mæsse, with abbreviation of Cristes by the symbol X, orthographic borrowing from Ancient Greek Χ (Kh, letter chi), from Χριστός (Khristós, “Christ”). By surface analysis, X (“Christ”) + -mas (“holiday”). In popular use since late 19th century. See Wikipedia for more information.
Often used in writing to save space; sometimes pronounced as 'Christmas' even when written as 'Xmas'.