(countable) A place (building, office, shop, or counter) concerned with the business of delivering letters, post or mail and selling stamps, etc. / (countable) An organisation that delivers letters.

plural of post office

(rail transport, UK) a type of railway coach designed for the carriage and sorting of mail en route.

A uniquely addressable lockable box located on the premises of a post office that may be hired as collection point for mail. / (electricity) A test instrument once used by telephone engineers.

plural of post office box

(archaic) Synonym of postal order

plural of post office order

(historical) Alternative form of post-office order.

plural of post-office order

Alternative form of post office box and PO box.