Why Spain's Language Is Called "Castellano" (and Also "Español")

The terms castellano and español refer to the same language—the Romance tongue originating in the medieval Kingdom of Castile and now spoken by ~500 million native speakers worldwide.

Etymology & Usage

• Castellano: "Language of Castile" (Castilla). Used in the Spanish Constitution (1978), Article 3: "Castellano es la lengua española oficial del Estado." Preferred in Spain's multilingual regions (Catalonia, Basque Country, Galicia, Valencia) to distinguish it from co-official languages (català, euskara, galego, valencià).
• Español: Derived from Hispania (Roman name for Iberian Peninsula). Dominant in Latin America and international contexts (ISO 639-1 code: es).

Official Policy (Real Academia Española)

"Ambas denominaciones son válidas... español es la recomendada para uso internacional; castellano para referirse a la lengua en el contexto de las lenguas cooficiales de España."

Regional Preferences

Bottom Line

Castellano = Español. The dual nomenclature reflects political history, not linguistic difference. Use español globally; use castellano when speaking in/about Spain's multilingual context.