Possible Duplicate:
Why do some words have “X” as a substitute?
I went to Online Etymology and this is what I found:
"Christmas," 1551, X'temmas, wherein the X is an abbreviation for Christ in Christmas, from first letter of Greek Christos "Christ". The earlier way to abbreviate it was Xp- or Xr-, corresponding to "Chr-," and the form Xres mæsse for "Christmas" appears in the "Anglo-Saxon Chronicle" (c.1100).
But I fail to understand how did this transform happen? Mention in popular culture or books would be greatly appreciated.
