n (context|musical instruments) A woodwindinstrument consisting of a metal, wood or bamboo tube with a row of circular holes and played by blowing across a hole in the side of one end or through a narrow channel at one end against a sharp edge, while covering none, some or all of the holes with the fingers to vary the note played.
n A glass with a long, narrow bowl and a long stem, used for drinking wine, especially champagne.
n A helical groove going up a drill bit which allows the drilled out material to come up out of the hole as it's drilled.
n (architecture|firearms) A semicylindrical vertical groove in a pillar, or a similar groove in a rifle barrel used to cut down the weight.