Declivity
Declivity , noun
[Latin declivitas, from declivis sloping, downhill; de + clivus a slope, a hill; akin to clinare to incline: compare French déclivité. See Decline.]
1.
Deviation from a horizontal line; gradual descent of surface; inclination downward; slope; -- opposed to acclivity, or ascent; the same slope, considered as descending, being a declivity, which, considered as ascending, is an acclivity.
2.
A descending surface; a sloping place.
Commodious declivities and channels for the passage of the waters.