Medieval Spanish and Basque name of uncertain meaning and origin. Very common name during the middle ages, specially in the Álava province of the Basque country. In other regions of Spain it has been found mainly as a female name, probably a contraction of Eulalia or Eloísa. Other hypothesis say it's derived from Visigothic name Egilona.Eylo or Gilo was the first attested count of Álava during the 9th century. Eylo Alfonso (1075-1109), Leonese noblewoman who founded several churches and hospitals in Valladolid, and wife of count Pedro Ansúrez.