First attested in 1614. From Latin acclīvitās, from acclīvis ("ascending"), from ad + clīvus ("slope").

• IPA: /əˈklɪv.ə.ti/

acclivity (plural acclivities)

1. (geomorphology) 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.
   • 1912 January, Zane Grey, chapter 8, in Riders of the Purple Sage […], New York, N.Y., London: Harper & Brothers Publishers, →OCLC ↗:

     Just below it leaned a tottering crag that would have toppled, starting an avalanche on an acclivity where no sliding mass could stop.

• Portuguese: aclividade