Languid lip
The sharp edge at the mouth of a flue organ pipe against which the air stream produces the tone.
What it means
The lip is the sharp edge at the front of a flue pipe's mouth against which the air stream leaving the flue is directed. Vortices formed at this edge excite the air column inside the pipe to its characteristic pitch.
In the notation
The lip does not appear in the score, only in descriptions of organ building.
Musical use
An upper and lower lip are distinguished: the lower lip sits at the foot of the pipe above the languid, the upper lip at the lower edge of the pipe body. The shape, height and cut of the lip strongly affect a pipe's tone color and speech, and are among the most important tools of voicing. The lip is distinct from the languid, the thin sheet that directs the air stream toward the lip but does not itself form an edge.