Source : Webster's Revised Unabridged Dictionary (1913)

Dago \Da"go\ (d[=a]"g[-o]), n.; pl. {Dagos} (-g[=o]z). [Cf. Sp.
   Diego, E. James.]
   A nickname given to a person of Spanish (or, by extension,
   Portuguese or Italian) descent. [U. S.]

Source : WordNet®

dago
     n : offensive terms for a person of Italian descent [syn: {wop},
          {Guinea}, {greaseball}]
     [also: {dagoes} (pl)]