Aljam´ıa historically meant Arabic-speaking competence, not a writing system

Evidence

Some specialists in other fields, having come across the sense of “Spanish in Arabic characters” for aljam´ıa, jump to the conclusion that this is the primary and only correct usage. And hence they are in danger of misinterpreting some early texts. When Cervantes spoke in Don Quixote of a moro aljamiado de Toledo, for example, he was not thinking of the writing of texts in Spanish in Arabic characters, he was simply thinking of a Muslim from Toledo “with a good command of Spanish.” — L. P. Harvey, Muslims in Spain, 1500 to 1614, 625

Categorization

• DEFINE: Clarifies the two distinct senses of aljam´ıa: the historical meaning (Spanish spoken/commanded) vs. modern academic usage (Spanish written in Arabic characters).
• XREF: Parallels the word ‘morisco’ ambiguity Harvey likely discusses elsewhere in the book — same pattern of medieval vs. modern academic meaning drift.
• CANDY: A tidy trivia bit: Cervantes’ moro aljamiado was not writing in Arabic characters but just spoke good Spanish.