The Spanish word for Spanish is `` EspaÃ ol '' , and the Spanish word for Castilian is `` Castellano '' . The Spanish Royal Academy uses the term espaÃ ol ( rather than `` castellano '' ) in its publications , due to the fact that `` the term derives from the Provenzal word espaignol , which in turn derives from the Medieval Latin word Hispaniolus , which means ` from -- or pertaining to -- Hispania ' '' . The Diccionario PanhispÃ nico de Dudas ( a linguistic guide published by the Spanish Royal Academy ) states that , although the Spanish Royal Academy prefers to use the term espaÃ ol in its publications when referring to the Spanish language , both terms ( espaÃ ol and castellano ) are regarded as synonymous and equally valid .