Meaning

noun (ethnic slur) offensive term for a person of Italian descent

originAlteration of diego (“Spaniard”), from Spanish Diego (common Spanish name) by law of Hobson-Jobson. The term originated among sailors from the Northern United States, first attested in Boston in 1838. "Diego" is the Portuguese nickname for any deckhand. After transforming into "dago" in English, the word gradually came to denote any southern European in a generic manner. From there, the word…

Etymology from Wiktionary, CC BY-SA 3.0