"Why are passengers called "pax"?
1 Answer
Mercedes R. Lackey
Mercedes R. Lackey, works at Self-employed Writer
Answered Jun 28, 2016 · Author has 6.5k answers and 17.4m answer views
It goes back to the days in airline transportation when everything about a flight was sent to the destination airport/airline by Telex. The number of characters you could send in a single message was limited…not unlike Twitter and text messaging. The “x” appended to something that was an abbreviation was the sign that it was an abbreviation—there were others, such as Wx for “weather.” Since the term was fairly obvious and convenient, it got picked up by other forms of transportation, and even hotels!"
https://www.quora.com/Why-are-passengers-called-pax