The angle at a point on the earth between the direction of a plumb line (the vertical) and the perpendicular (the normal) to the reference spheroid; this difference seldom exceeds 30 seconds of arc.

1. An angle that measures the departure of a moving object from its directed course.

2. The angle of a deflection shot in gunnery, measured between the line of sight to the target and the line of sight to the aiming point.