Lewis & Short

2. Trĕbĭa, ae, f., a village in Umbria, now Trevi, Arn. 3, 122.
Hence,

  1. A. Trĕ-bĭānus, a, um, adj., of or belonging to Trebia, Trebian: ager, Liv. 23, 14, 13: di, Arn. 3, 126.
    In plur. subst.: Trĕbĭāni, ōrum, m., the inhabitants of Trebia, Suet. Tib. 31.
  2. B. Trĕbĭātes, um, m., the inhabitants of Trebia, Plin. 3, 14, 19, § 114.