What does acclivity mean?
The definition of acclivity
Ac*cliv”i*ty, n.; pl. Acclivities.
Etym: [L. acclivitas, fr. acclivis, acclivus, ascending; ad + clivus a hill, slope, fr. root kli to lean. See Lean.]

A slope or inclination of the earth, as the side of a hill, considered as ascending, in opposition to declivity, or descending; an upward slope; ascent.