a ticket that allows the traveller to depart from a different airport to the one in which they landed. For example you could fly from London to Sydney but return to London from Perth. See Surface Sect [..]

Flying into one city and out of another city. The path of the flights forms a shape that resembles an open jaw. Airlines’ policies vary greatly in terms of their allowance of open-jaws on award travel.

You can fly to a destination and return to the port of departure via a different destination. For example: Depart from Hong Kong to London, return to Hong Kong from Paris.