Emily Dickinson Lexicon

AC-CLIV'I-TY, n. [L. acclivus, acclivis, ascending, from ad and clivis, an ascent; Ir. clui; Gr. Eol. κλιπυς; Sax. clif, a cliff, bank or shore; clifian, cleofian, to cleave or split. See Cliff.]

A slope or inclination of the earth, as the side of a hill, considered as ascending, in opposition to declivity, or a side descending. Rising ground; ascent; the talus of a rampart.