A streamliner is a vehicle incorporating streamlining in a shape providing reduced air resistance. The term is applied to high-speed railway trainsets of the 1930s to 1950s, and to their successor "bullet trains". Less commonly, the term is applied to fully faired upright and recumbent bicycles. As part of the Streamline Moderne trend, the term was applied to passenger cars, trucks, and other types of light-, medium-, or heavy-duty vehicles, but now vehicle streamlining is so prevalent that it is not an outstanding characteristic. In land speed racing, it is a term applied to the long, slender, custom built, high-speed vehicles with enclosed wheels.

Streamline Moderne is an international style of Art Deco architecture and design that emerged in the 1930s. Inspired by aerodynamic design, it emphasized curving forms, long horizontal lines, and sometimes nautical elements. In industrial design, it was used in railroad locomotives, telephones, toasters, buses, appliances, and other devices to give the impression of sleekness and modernity.