What is it with this word "pax"? It seems to be creeping more and more into usage in replacing the word "person" or "persons". It manifests in commercial contexts such as: “$10 per pax”; “minimum 20 pax per departure”; "10 pax per table"; "the bus seats 30 pax", and so on. It can appear in  brochures, advertisements, notices or just simple conversation on anything ranging from dinner reservations, to tour bookings.

I'm not sure if it's a worldwide phenomenon, but it is certainly entrenching itself in Singapore.

To begin with, the word indeed exists in English dictionaries. It derives from Pax, the Roman Goddess of peace, and is generally defined to refer to a period of general peace, especially one in which there is one dominant nation. For example, Pax Romana refers to the long period of stability under the Roman Empire. There are a couple of other ancillary meanings bearing ecclesiastical leanings that I shan't venture into given their remoteness.

However, in all these definitions, whatever they are, there is not the remotest connection in support of the meaning which the above quoted contexts seek to convey, viz. "person" or "persons".

So just how on Earth did this word come to muscle its way into everyday commercial usage, albeit illegitimately?  

I reckon the latter traces its origins to the abbreviation for "passenger" used in the travel industry.  Just as the aviation world abridged "Los Angeles" to "LAX" and "Kansai" to "KIX", tri-syllabic "passenger" became a fashionable "PAX" simpliciter – easy on the tongue and speedily verbalised under the demands of haste and despatch, conditions so often enjoined in the industry.

But how did this abridged word come to gain popular acceptance in everyday parlance so unconnected with the traveling passenger, for example, diners in a restaurant?

Put it down to Singaporeans’ penchant for acronyms and cursory expression.  Why waste precious seconds verbalizing more when you can convey the same in less?

Throw in for good measure a generation educated in rote learning and a society accustomed to obsequious conformity and mechanical routine.

Valiant supporters of "pax" would argue that it doesn't matter that the abridged product draws no legitimate connection with "person" or "persons", as long it conveys a meaning understood by the target audience. Certainly, but unlike the benefit of space-saving and linguistically expeditious LAX over Los Angeles, what advantage is there to be derived in the relatively marginal abridgment of "person" or "persons" to "pax" when it has to suffer the ignominy of bastardizing the language?