Rabbi
in Jewish history and literature, rabbi is the noun Rab with the pronominal suffix, and in Biblical Hebrew= great man, distinguished for age, rank, office or skill. In post-Biblical Hebrew it is used as a title indicating sundry office or skill. In post-Biblical Hebrew degrees by its several terminations.
Thus, the simple term Rab=teacher, master, and was the title which Babylonion Jews gave to a doctor of the law.