It means ‘the cid.”
Rodrigo DÃaz de Vivar (c. 1043 – 1099) was a Castilian nobleman and military leader in medieval Spain. He was called El Cid (the Lord) by the Moors and El Campeador (the Outstanding Warrior) by Christians. He was born in Vivar, a town near the city of Burgos. After his death, he became the legendary national hero of Castile, and the protagonist of Cantar de Mio Cid, a medieval Spanish epic poem