acclivity

/ə.ˈklɪv.ə.ti/

IPA: /AE0 K L IH1 V AH0 T IY0/

noun
  1. 1

    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.

Source: https://en.wiktionary.org/wiki/acclivity