| dip [dip] ENGINEERING The vertical angle between the sensible horizon and a line to the visible horizon at sea, due to the elevation of the observer and to the convexity of the earth's surface. Also known as dip of horizon. GEOLOGY 1. The angle that a stratum or fault plane makes with the horizontal. Also known as angle of dip; formation dip; true dip. 2. A pronounced depression in the land surface. |