smokestack

noun

1. A conduit or group of conduits atop a structure allowing smoke to flow out, as on a steam locomotive, ship, factory, or power plant using fossil fuels.

   “With its long tapered cowcatcher, massive headlamp and enormous diamond smokestack behind, wagon-top boiler, high running-plate above the driving-wheels reached from a front door in the square side-window cab, cylinders with slide valves mounted on top, and double bogie tender, General in its present form is typical of much earlier American locomotive practice.”