1. n. [Geology]

The orientation of a planar or linear feature in three-dimensional (3D) space. Planar features that are not horizontal, such as tilted strata, are described by their strike, or the azimuth of the intersection of the plane with a horizontal surface, and the dip, or the magnitude of its inclination from a horizontal reference. The trend and plunge of linear features, such as the axis of a fold, describe the azimuth of the line and its deviation from horizontal.

See: apparent dip,  dipping bed,  lithologic contact,  true stratigraphic thickness,  true vertical thickness