Thanks to this post from Grammar Girl!
Many listeners have asked about the origin and appropriateness of “Xmas.”
Retailers have long been accused of secularizing Christmas by using “Xmas” in signs and advertisements; therefore, I suspect many of you will be surprised to learn that “Xmas” has a religious origin.
In Greek, the letter “chi” is written as an X, and chi is the first letter of the Greek word for “Christ.” Greeks sometimes abbreviated “Christ” as “X.” For example, they abbreviated “Christ savior” as “XP.” (“P” is the symbol for the Greek letter “rho,” which is the first letter of the word “savior” in Greek.) TheOxford English Dictionary shows the first known English use of “Xmas” in 1551.
As for appropriateness, “Xmas” may have a religious origin and fit better on signs, but many people — both those who use “Xmas” and those who complain about its use — are unaware of the religious origin. If you choose to use “Xmas,” you should know that some people will be infuriated.
I know that I actually found this fascinating as I was “one” of those who NEVER dared used Xmas in place of Christmas, even if I needed to shorthand something really quick. I guess that proves we shouldn’t jump to conclusions on anything.