Before revision: 250px|d = run Δh = rise l = slope length α = angle of inclination The grade ( also called stepth, slope, incline , gradient , mainfall, pitch or rise) of a physical feature, landform or constructed line refers to the tangent of the angle of that surface to the horizontal.
After revision: 250px|d = run Δh = rise l = slope length α = angle of inclination The grade ( also called stepth, slope, incline US) or gradient (UK) ( , mainfall, pitch or rise) of a physical feature, landform or constructed line refers to the tangent of the angle of that surface to the horizontal.