Etymology of "Christmas"

It's interesting that the earliest record of the use of the term Christ Mass comes more than a millenium after the putative birth of Jesus.

"The word Christmas originated as a compound meaning "Christ's Mass". It is derived from the Middle English Christemasse and Old English Cristes mæsse, a phrase first recorded in 1038. "Cristes" is from Greek Christos and "mæsse" is from Latin missa (the holy mass). In Greek, the letter Χ (chi), is the first letter of Christ, and it, or the similar Roman letter X, has been used as an abbreviation for Christ since the mid-16th century. Hence, Xmas is sometimes used as an abbreviation for Christmas."

-Wikipedia http://en.wikipedia.org/wiki/Christmas

According to the "On-line Etymology Dictionary" Christ Mass was first written as one word around the mid-14th century (1300's).