'Flue pipe' definitions:

Definition of 'flue pipe'

noun

Organ pipe whose tone is produced by air passing across the sharp edge of a fissure or lip [syn: flue pipe, flue, labial pipe]

From: GCIDE

Flue pipe \Flue pipe\ (Music) A pipe, esp. an organ pipe, whose tone is produced by the impinging of a current of air upon an edge, or lip, causing a wave motion in the air within; a mouth pipe; -- distinguished from reed pipe. Flue pipes are either open or closed (stopped at the distant end). The flute and flageolet are open pipes; a bottle acts as a closed pipe when one blows across the neck. The organ has both open and closed flue pipes, those of metal being usually round in section, and those of wood triangular or square. [Webster 1913 Suppl.]