dip, angle of dip, magnetic dip, magnetic inclination, inclination(noun)

(physics) the angle that a magnetic needle makes with the plane of the horizon

magnetic dip(Noun)

The angle between magnetic north and the horizontal (as shown by a compass held vertically).

Magnetic Dip

The inclination from the horizontal assumed by a magnetic needle free to move in the vertical plane. (See Magnetic Elements.) The angle of dip or inclination is entirely a function of the earth, not of the needle.