Large merchant ship that visits designated ports on a regular schedule, carrying whatever cargo and passengers are available on the date of sailing. The first liners were operated in the North Atlantic, notably by Samuel Cunard of Britain, beginning in 1840. Their heyday lasted from the late 19th to the mid-20th century. Many were extraordinarily luxurious. Among the most famous were Cunarders such as the Mauretania and the Queen Mary; the German Vaterland (later renamed Leviathan), for many years the largest ship afloat; the ill-fated Titanic; and the United States. Their reign ended in the 1960s with the rise of jet travel, but liners ranging from cruise ships to refrigerated cargo ships continued to sail