Fluctuación prefijal en el gallego-portugués y en el castellano medievales

In Galician-Portuguese and in Old Castilian the coexistence of verbs with and without prefix ( acuydar and cuydar, esguardar and guardar ) that are semantically equivalent or with close meanings is attested. At the same time, in the current Spanish and Portuguese there are words like agradecer , not previously prefixed ( gradecer ). Both processes of prefix loss and prefix addition operate within the framework of the fluxes of variation and change of that period, commonly resulting in the overlap of one of the words during or after the Middle Ages. We propose to investigate the motivations of these different prefix trajectories, considering the structure of the verbal base, the nature of the prefix, in Latin and in Romance, and the external factors that support (i) the coexistence, during several centuries, of both forms sharing the same root or (ii) the loss of such coexistence.