Lewis & Short

Sĕgūsĭāvi, ōrum, m., = Σεγοσιανοί or Σεγουσιανοί, a people in Gallia Lugdunensis, neighbors of the Allobroges and Aedui, in the mod. Feurs (Dép. de la Loire), Caes. B. G. 1, 10 fin.; 7, 64; 7, 75; Cic. Quint. 25 fin.
Sing.
SEGVSIAVVS, Inscr. Orell. 5217. They are also called Secusiavi liberi, Plin. 4, 18, 32, § 107.