pay-train1
/ˈpeɪˌtreɪn/noun
A train carrying wages. Now historical.
Origin
Mid 19th century. From pay + train.
pay-train2
/ˈpeɪˌtreɪn/noun
A rail service on which tickets are bought on the train itself rather than at the station before boarding.
Origin
1960s. From pay + train. Compare earlier pay-train.