Hastings' Dictionary of the Bible (1898)
RAB'BI, a title of dignity, literally signifying "my master." It was given by the Jews to distinguish teachers of their Law, and frequently applied to our Lord by the disciples and the people. Matt 23:7-8, Gen 26:25, Matt 26:49; Mark 9:5; Jer 11:21; Mark 14:45; John 1:38, Lev 14:49; 2 Sam 3:2, Gal 3:26, etc. The usual Greek word in the Gospels as the title of Christ is "teacher." Matt 8:19; Eze 9:11, etc. The Jews distinguished between Rab,
"master," Rabbi, "my master," and Rabboni, "my great master." The last was the most honorable title of all.