It is not Castilian but a Galician or Asturian word for 'gijonés' ("native of Gijón"). See Galician/Xixonés , Asturian/Xixonés .
A person born in Gijón, a city in Asturias (Spain). In Spanish it is written gijonés, being xixonés its version in bable or asturian, which is an autochthonous language of Asturias, which like other Romance languages, comes from Latin.