Lewis Short
arbītrātor (noun M) : id., in late Lat. = arbiter, II. B.
* A master, ruler, lord: JVPPITER ARBITRATOR,Inscr. Gud. 7, 5.—Hence a place in the tenth district at Rome is called Pentapylon Jovis arbitratoris, Publ. Victor. Reg. 10.
Charlton T. Lewis, Charles Short, A Latin Dictionary