1. The angle between a line’s direction and the horizontal; e.g., magnetic inclination, the angle at which magnetic lines of force dip. 2. The dip of a plane (bed, fault, or other tabular body) measured from the horizontal. The attitude of the plane may be characterized by the direction of a line normal to it and the inclination of the plane by the angle between its normal and vertical. 3. The angle between the orbital plane of a satellite and the Earth’s equatorial plane.