A propliner is a large, propeller-driven airliner. Typically, the term is used for piston-powered airliners that flew before the beginning of the jet age, not for modern turbine-powered propeller airliners. Propliners featured all-metal wings and structural members, retractable landing gear, and generally two or four engines.
The first propliner was the Boeing 247 (1933), with the Douglas DC-1 and DC-2 closely following. The most successful is the Douglas DC-3, which was produced in the thousands, and is still in widespread use. Other American-designed propliners included the DC-4, DC-5, DC-6, and DC-7; the Lockheed Constellation and Starliner; the Martin 2-0-2 and 4-0-4; the Convair CV-240; and the Boeing Stratocruiser.