Lewis & Short

Ŏpĭtergĭum, ii, n.,

  1. I. a city of Italy, in the territory of the Veneti, now Oderzo, Plin. 3, 19, 23, § 130; Tac. H. 3, 6.
    Hence,
  2. II. Ŏpĭtergīnus, a, um, adj., of or belonging to Opitergium, Opitergian, Plin. 3, 18, 22, § 126.
    Plur. subst.: Ŏpĭtergīni, ōrum, m., the inhabitants of Opitergium, the Opitergians, Flor. 4, 2, 33.