Easton's Bible Dictionary: M. G. Easton, M.A., D.D.
My master, a title of dignity given by the Jews to their doctors of the law and their distinguished teachers. It is sometimes applied to Christ (Mt. 23:7, 8; Mk. 9:5 (R.V.); Jn. 1:38, 49, 3:2, 6:25, etc.); also to John (Jn. 3:26).