The Lamanite word "Rabbanah" obviously has the same derivation and meaning as the Hebrew word, Rabboni (Jn 20:16) or Rabbi.
"Rabbanah is a wonderful word. Translated, it means powerful, or great king. In applying that name to Ammon, the servants of Lamoni did not know that in reality he was a prince, the son of the mighty king of the Nephites. But after Ammon's miraculous exploits at the Waters of Sebus, they regarded him, as did their master, something more than a man." (Reynolds and Sjodahl, Commentary on the Book of Mormon, vol. 3, p. 265)