sēmĭ-circŭlus, a, um, adj., semicircular: ager, Col. 5, 2, 8. Hence, subst.: sēmĭ-circŭlus, i, m., a half-circle, semicircle (syn. semiorbis): uncus in semicirculi speciem, Cels. 7, 26, 2: ager, i. e. semicircular, Col. 5, 2, 8.