Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Hortānum, i, n., a city of Etruria (probably called after the Etruscan goddess Horta, Paul. ex Fest. 4, 8; cf. Müll. Etrusk. II. p. 62), now Orte, Plin. 3, 5, 8, § 52.
Hence, Hortīnus, a, um, of Hortanum: classes, Verg. A. 7, 716.