(1):
(n.) An inclosed passage way for establishing and directing a current of air, gases, etc.; an air passage
(2):
(n.) A passage way for conducting a current of fresh, foul, or heated air from one place to another.
(3):
(n.) In an organ flue pipe, the opening between the lower lip and the languet.
(4):
(n.) A pipe or passage for conveying flame and hot gases through surrounding water in a boiler; - distinguished from a tube which holds water and is surrounded by fire. Small flues are called fire tubes or simply tubes.
(5):
(n.) Light down, such as rises from cotton, fur, etc.; very fine lint or hair.
(6):
(n.) A compartment or division of a chimney for conveying flame and smoke to the outer air.