declivity

The downward slope of a curve.

The Declivity was ſo ſmall, that I walked near a mile before I got to the Shore, which I conjectur'd was about eight a-clock in the Evening.

1780, Theodore Augustine Mann, A Treatise on Rivers and Canals, Philosophical Transactions of the Royal Society of London, Volume 69: For the Year 1779, Part II, 582, The velocity of flowing waters is very far from being in proportion to the quantity of declivity in their bed: […] .

A downward bend in a path.

An inward curve of the exoskeleton of an insect, such as between body segments; a segment of an insect's body where the exoskeleton curves inward.

1979, Entomology Circular, Issue 200, Part 366, Division of Plant Industry, page number not shown, Males of all species have more developed armature of the elytral declivity than females (Figs. S, 6, 8, 9, 11-14).

Propodeum in profile with upper lobe of declivity elongate and narrow, subspiniform, almost as long as lower lobe.