The word RAB in Hebrew signifies chief; thus Nebuzaradan is the chief or captain of the guard, 2 Kings 25:8 , in Hebrew rabtabbachim; so Ashpenaz is the rab, chief or master of the eunuchs, and Daniel of the mag, Daniel 1:3 5:11 . See RAB-MAG . At a later period, it was introduced as a solemn title of honor in the Jewish schools, meaning master, teacher, and doctor. There were various distinctions and degrees; the term rab was accounted the least honorable; that of rabbi, signifying my master, being of higher dignity.
Another form of the word was rabban or rabbon, from which comes also rabboni, John 20:16; this was regarded as the highest title of honor, and was never formally bestowed on more than seven persons, who all belonged to the celebrated school of Hillel, and were preeminently distinguished by their rank and learning. See Matthew 23:7,8 . It was a title often given to the Saviour both by his disciples and the people, Mark 9:5 10:51 11:21 John 1:38,49 4:31 .