Pax in commercial transport is used as something like persons or passengers, in the context of counting people, e.g. 150 pax onboard.

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(Amadeus capture, source)

I observed that in German writers tend to use the meaning:

PAX = Persons approximately.
(Source: European Union and the Committee of the Regions)

English.SE has a page for What does “pax” mean in the context of the apartment rental? Selected answer:

Pax isn't exactly shorthand for Passengers. It's short for Passengers and Passes.

But the author of the answer agreed that another answer was likely more accurate. The latter has a reference to a magazine, Air Facts: The Magazine for Pilots - 1946:

Cargo is known as "cargo", but passengers are called "pax" by the traffic department, who puts them on and takes them off the airplane and "bodies" by the crews who fly them.

Pax could be from passenger as usually assumed in the Aviation community, albeit I don't see why not *pass" instead. I wouldn't be surprised it comes from the merchant navy.

Can we track the use further back to the origin in aviation field?

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    $\begingroup$ Might be better asked on english.stackexchange.com where you can inquire about the etymology of certain phrases. I don't think its specific to aviation, pretty much any industry that caters to passengers uses "pax" as an abbreviation, so aviation may just borrow it from an unrelated field. $\endgroup$
    – Ron Beyer
    Feb 12, 2016 at 14:34
  • $\begingroup$ @mins Would be interesting to know if it was in use during the steamship era too e.g. pre 1920. $\endgroup$ Feb 12, 2016 at 14:50
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    $\begingroup$ FYI, I am ex-military (air force) and never heard pax used except to mean passenger. $\endgroup$
    – Simon
    Feb 12, 2016 at 16:09
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    $\begingroup$ @curious_cat I wonder if some of the uses of pax from 1800s and earlier were related to the Latin word meaning 'peace' (e.g. the "Pax Romana") rather than as an abbreviation for 'passengers' as it's used in aviation? $\endgroup$
    – reirab
    Feb 12, 2016 at 16:43
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    $\begingroup$ when I worked in the airline technology business, IATA was the authoritative source of data processing systems. according to IATA, PAX means passenger. you can find lots of references googling 'IATA PAX' $\endgroup$
    – rbp
    Feb 12, 2016 at 17:44

2 Answers 2


The 'x' suffix is aviation speak in an abbreviated word called a contraction. You can think of the 'x' as "cut short" shorthand. Some are defined in manuals or advisory circulars. For example, WX is weather as defined in an old advisory circular, AC00-45.

Official or not, a few others that come to mind are:

MX - maintenance
CX - cancel
TX - transmit
RX - receive

Maybe others will chime in the comments with more lore. The -x is also used outside of aviation, and is a common abbreviation marker, e.g. Dx ("diagnosis"), elex ("election"), and Hx ("history").

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    $\begingroup$ This is the first time I read this explanation which is very plausible, do you have any document that could support it? $\endgroup$
    – mins
    Jun 9, 2017 at 17:58
  • $\begingroup$ Please see the link contraction in my answer, for example. The right-hand column of that government document shows a source. $\endgroup$
    – STWilson
    Jun 9, 2017 at 18:12
  • $\begingroup$ Perhaps my answer missed the root of your question, origin being the earliest use. Having been in aviation my life, cutting words short in log entries and aviation reports with 'x' has been commonly understood. $\endgroup$
    – STWilson
    Jun 9, 2017 at 18:19
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    $\begingroup$ Rx & Tx are common for Receive & Transmit in the computer world, as well - look at your router/modem & you will, most likely see a light for each. $\endgroup$
    – FreeMan
    Jun 9, 2017 at 20:27
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    $\begingroup$ Related: en.wikipedia.org/wiki/X In abbreviations, it can represent "trans-" (e.g. XMIT for transmit, XFER for transfer), "cross-" (e.g. X-ing for crossing, XREF for cross-reference), "Christ-" as shorthand for the labarum (e.g. Xmas for Christmas, Xian for Christian), the "crys-" in crystal (XTAL), or various words starting with "ex-" $\endgroup$
    – UKMonkey
    Jul 9, 2018 at 13:53

Pass would not be used as in the old days employees travelled on a 'pass'instead of a ticket. It could also be confused with the verb.

As a side note .. I seem to remember the plural was PAX and singular was PAP... eg 1PAP, 3PAX.


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