windage
wind.age \'win-dij\ n 1a: the space between the projectile of a smoothbore gun and the surface of the bore 1b: the difference between the diameter of the bore of a muzzle-loading rif le cannon and that of the projectile cylinder 2a: the amount of sight deflection necessary to compensate for wind displac ement in aiming a gun 2b1: the influence of the wind in deflecting the course of a projectile 2b2: the amount of deflection due to the wind 3: the disturbance of the air caused by a passing object (as a projectile) 4: the surface exposed (as by a ship) to the wind
Webster's English Dictionary