Lewis & Short

Cottĭus, ii, m.,

  1. I. the name of two kings of northern Italy, the father, who was a contemporary and friend of Augustus, Amm. 15, 10, 2 and 7, and the son (cf. Dio Cass. 60, 14), after whose death Nero made the country a Roman province, Suet. Ner. 18; id. Tib. 37; Aur. Vict. Caes. 5, 2.
    Hence,
  2. II. Adjj.
      1. 1. Cottĭus, a, um, Cottian: Alpes Cottiae, the Cottian Alps, west of Augusta Taurinorum, whose highest point is Alpis Cottia, now Mont Genèvre, Tac. H. 1, 87; Amm. 15, 10, 2.
      2. 2. Cottĭānus, a, um, the same: civitates, Plin. 3, 20, 24, § 135: Alpes, Tac. H. 1, 61; 4, 68.