最佳解答: Ocean liner
An ocean liner is a passenger ship or passenger-cargo ship which tranports people and often freight from one port to another along regular trans-oceanic routes according to a schedule. The term also refers to vessels designed to engage in such trades, even if temporarily used for other purposes (such as on cruises or as troopships). The category does not include ferries or other vessels engaged in short-sea trading, nor cruise ships where the voyage itself, and not transportation, is the prime purpose of the trip. Nor does it include tramp steamers even if equipped to handle limited numbers of passengers, nor other cargo vessels (although many shipping companies refer to themselves as "lines" and their container ships, which often operate over set routes according to established schedules, as "liners"). Ocean liners typically were strongly built with high freeboards to withstand sea states and adverse conditions encountered in the open ocean, and had large capacities for fuel and other stores which would be consumed on their multi-day or mulit-week voyages.
Ocean liners were the primary mode of intercontinental travel for over a century, from the mid-19th century to the 1960s, when they were finally supplanted by airliners. In addition to passengers, liners also carried mail and cargo. Ships contracted to carry British Royal Mail used the designation RMS. Liners were also the preferred way to move gold and other high value cargos.