Lewis Short
mystăgōgus (noun M) = μυσταγωγός:
* One who conducts a person through secret and sacred places as a guide, an initiator, a mystagogue, Cic. Verr. 2, 4, 59, § 132.— Trop.: amicitiae meae, te mystagogo usus, accessit,the founder,Symm. Ep. 5, 64.
Charlton T. Lewis, Charles Short, A Latin Dictionary