n.1. a. The effect of wind on the course of a projectile.
b. The point or degree at which the wind gauge or sight of a rifle or gun must be set to compensate for the effect of the wind.
c. The difference in a given firearm between the diameter of the projectile fired and the diameter of the bore of the firearm.
2. The disturbance of air caused by the passage of a fast-moving object, such as a railway train.
3. Nautical The part of the surface of a ship exposed to the wind.