We don't have synonyms for advocatus yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are advocate, advocates and advocator.
(n) :
(historical) A medieval officeholder, particularly important in the Holy Roman Empire, who was delegated some of the powers and functions of a major feudal lord, or for an institution such as an abbey.
(n) :
(historical) A medieval officeholder, particularly important in the Holy Roman Empire, who was delegated some of the powers and functions of a major feudal lord, or for an institution such as an abbey.