Xmas does not mean Christmas. And the reason is as simple as can be explained in two sentences. The latter the most important:
The problem with the x = Chi explanation that so many love to spew from their keyboards and mouths during this season is that the general public knows NOTHING of it, or Greek. And, most importantly of all, all they see is an x, and in Greek, x is Xi, not Chi.
If you’re going to foist a ridiculous pseudo-explanation on the public in an attempt to justify laziness in abbreviation, please, at least learn enough Greek to know the difference between χ and ξ . Otherwise, you just look silly.
And, by the by, the early church did abbreviate χριστος- but NEVER with just χ. When they did, it was χρ with a line over it so you knew it was an abbreviation. People who tell you they just used x are stupid, or liars, or stupid liars.
In sum- NO, you have NEVER heard someone say -‘Chi- mas’ but you’ve heard plenty of people say ‘X-mas’ because to them X is X.
Thus endeth the lesson.
Amen, and amen.