What is Supernumerarii?

Legal Definition
Rom. civil law. From the reign of Constantine to Justinian, advocates were divided into two classes: viz. advocates in title, who were called statute, and supernumeraries. The statutis were inscribed in the mat-riculation books, and formed a part of the college of advocates in each jurisdiction. The supernumeraries were not attached to any bar in particular, and could reside where, they pleased; they took the place of advocates by title, as vacancies occurred in that body. Code Justin., de adv. div. jud. c. 3, 11, 13; Calvini Lex, ad voc.; also Statuti.
-- Bouviers Law Dictionary
Legal Definition
Lat. In Roman law. Advocates who were not registered or enrolled and did not belong to the college of advocates. They were not attached to any local jurisdiction. See Statuti.
-- Black's Law Dictionary