Medieval charters played a fundamental role in establishing rights and duties between the king and local communities. In Portugal, until the reign of D. Dinis (1279–1325), all official documentation from the royal chancellery was exclusively in Latin, although Portuguese had long circulated as a spoken language, but also in writing in unofficial contexts. Therefore, the first charters constitute a privileged corpus for the study of the Portuguese language, since the same content, in both Latin and Portuguese, is transmitted across various locations and time periods. The 12th and 13th centuries are a phase of transition and affirmation of Portuguese as a written language and these documents reflect it, as they contain forms and structures typical of Classical and Medieval Latin, as well as from the vernacular language. This article aims, on the one hand, to identify the vernacular lexical forms present in the charter of Santa Cruz de Vilariça, written in Latin, and to understand why they are incorporated into it; on the other hand, to analyse the syntactic structures typical of Portuguese that coexist with Latin casual syntax.
