For internal combustion engines, the pipe that vents waste gases from the engine.
On a steam locomotive, a pipe which takes away steam exhausted from a cylinder.
A pipe or duct that carries gaseous combustion products away from the point of combustion (such as a furnace).
In an organ flue pipe, the opening between the lower lip and the languet.
An enclosed passageway in which to direct air or other gaseous current along.