mid-15c., "kiss of peace," from Latin pax (genitive pacis) "peace," in Ecclesiastical Latin, "kiss of peace" (see peace). Capitalized, Pax was the name of the Roman goddess of peace. Used by 1933 with adjectives from national names, on model of Pax Romana (e.g. Pax Britannica, 1872; Pax Americana, 1886, with reference to Latin America).
A passenger: There were twenty pax listed for the trip
[1970s+; apparently derived fr passenger as prexy is fr president]
in Roman religion, personification of peace, probably recognized as a deity for the first time by the emperor Augustus, in whose reign much was made of the establishment of political calm. An altar of Pax Augusta (the Ara Pacis) was dedicated in 9 BC and a great temple of Pax completed by the emperor Vespasian in AD 75.