da·go also Da·go (dā'gō) n.
pl.da·gos also Da·gos or da·goes also Da·goesOffensive Slang Used as a disparaging term for an Italian, Spaniard, or Portuguese.
[Alteration of Spanish Diego, a given name, from Latin Iacōbus, Jacob.]
1823, from Sp. Diego "James," orig. used of Sp. or Port. sailors on Eng. or Amer. ships, by 1900 it had broadened to include non-sailors and shifted to mean chiefly "Italian."