noun / verb
slope
SLOHP/sləʊp/
The degree or direction of an upward or downward slant.
The grassy hillside slopes upward beside the climbing path.

Etymology
Middle English aslope, “on the incline,” is probably behind slope. The idea of a slant or oblique direction developed into a name for the slanting surface or ground itself.
In context
to prevent an accidentally moving vehicle when on a slope or hill, keep your automobile in park.