Dago is used in some traditions as a short form of Diego, a Spanish name related to James.
Dago is a given name of Spanish and Basque origin, functioning as a shortened or regional form of Diego — itself the Spanish evolution of Santiago, meaning Saint James. James derives from the Hebrew Ya'akov (Jacob), meaning 'supplanter' or, in later interpretation, 'may God protect.' The full chain from Dago back to the Hebrew patriarch Jacob is one of the longer and more surprising etymological journeys in the Western naming tradition.
In the Basque Country, Dago has historically been used as an independent given name rather than merely a nickname, and it appears in medieval Iberian records. The Basque language has its own ancient roots independent of Latin, and several Basque names survived the Romanization of the peninsula with their original forms intact. Dago sits within a cluster of short, vigorous Basque and old Spanish masculine names — Ander, Unai, Aitor — that have retained regional currency across centuries.
The name must be acknowledged to carry a separate and painful history in English: it became a derogatory ethnic slur in the United States by the late nineteenth century, used against Italian, Spanish, and Portuguese immigrants. For English-speaking families, this shadow makes Dago an unusual choice outside its home region. Within Spain, the Basque Country, and Latin America, however, it remains a legitimate historical name with no such connotation. The divergence illustrates how profoundly a word's meaning depends on the community speaking it.