Βέλγη

From LSJ

ἅλμην πιόντες ἐξαπῆλθον τοῦ βίου → they drank seawater and departed from life

Source

Spanish (DGE)

-ης, ἡ Belga ciudad quizá de la Galia Belga, Hsch.s.u. Βελγαῖος.