From Old Galician-Portuguese ezebro, from Vulgar Latin *eciferus (“fool, wild ass, donkey”), from Latin equiferus (“wild horse”), from equus (“horse”) and ferus (“wild”). Cognate with Portuguese zebro. Modern toponyms as Cebreiro are attested as Cebrario, Zebrario, Ecebrario and Ezebrario in local High Middle Ages Latin documents.