The Spanish Academy Dictionary conflates two historically distinct meanings of aljam´ıa

Evidence

With regard to the word itself, in its entry “aljam´ıa” the Spanish Academy Dictionary (Real Academia Espa˜nola, Diccionario de la lengua espa˜nola, s.v. “aljam´ıa”) gives a definition that leaves two quite distinct senses to exist side by side. They do not coincide, and they need to be distinguished. … Aljam´ıa: the name which the Moors [sic] gave to the Castilian language. Nowadays it is especially applied to the writings of the Moriscos in our language in Arabic characters. — L. P. Harvey, Muslims in Spain, 1500 to 1614, 620