Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
ac-clīvis, e, also (but much less freq.) -vus, a, um, adj. [ad + clivus], up hill, mounting upwards, ascending, steep: stadium, Lucil. ap. Non. 4, 11: ea viae pars valde acclivis est, Cic. Q. Fr. 3, 1, 2, § 4; so, leniter acclivis aditus, Caes. B. G. 2, 29 al.: acclivus, Ov. M. 2, 19.