flue

Short definition from Wiktionary

Noun

1. 1
   A pipe or duct that carries gaseous combustion products away from the point of combustion (such as a furnace).
2. 2
   An enclosed passageway in which to direct a current of air or other gases along.
3. 3
   A woolly or downy substance; down, nap; a piece of this.
4. 4
   In an organ flue pipe, the opening between the lower lip and the languet.

Adjective

1. 1
   Alternative form of flew (“shallow, flat”).