An offensive word that may derive from the name of a saint. H.L. Mencken
traces this disparaging term to 1832, when it was used in Louisiana to
describe a Spaniard, not an Italian. But dago is a corruption of the very
common Spanish name Diego, or alludes to St. Diego, Spain’s patron saint,
or both. Diego was used in Elizabethan times for a “swarthy” Spanish or
Portuguese seaman. As recently as the beginning of the 20th century the
word also meant the Italian language, and a professor or student of
Italian. The pejorative term is not heard as often today as its derivative
dago red, any cheap wine, which is sometimes uses by Italian-Americans
themselves. Dago may also come from “day come, day go,” a term reputedly
used by early Italian laborers in expressing their patient philosophy. Far
more offensive is wop, which arose toward the end of the nineteenth
century. This ugly word comes from a relatively innocuous one, the
Neapolitan guappo, a term used by immigrant laborers signifying a showy,
pretentious person. Similarly, the offensive guinea may have originally
referred to Italian laborers working for the equivalent of a guinea a day.