intake manifold

The manifold, usually on top of an engine, where air or a mixture of air and fuel enter an engines block through runners which are passages in the manifold leading to the engines cylinders

The Webby definition of manifold has the relevant one we're looking for: "A cylindrical pipe fitting, having a number of lateral outlets, for connecting one pipe with several others." An intake manifold is a part of an engine, typically an internal combustion engine. It consists of a length of piping with smaller pipes leading from it to the intake valves on the engine's cylinders. The intake manifold will contain and direct the flow of either fuel/air mixture, in the case of the carbureted or manifold injected engine, or regular air in the case of direct fuel injection systems such as the Volkswagen TDI which add their fuel directly into the cylinder before compression.