The name Cid is of Spanish origin, derived from the Old French word 'cid', meaning 'lord' or 'chief'. It was popularized by Rodrigo Díaz de Vivar, a medieval warrior known as 'El Cid', who adopted it as his nickname due to his military prowess and noble background. Today, Cid is still used as a given name for boys, carrying connotations of strength, nobility, and leadership, and remains associated with Spain despite gaining global popularity.