What is "ammah"

Ammah - a cubit, the name of a hill which Joab and Abishai reached as the sun went down, when they were in pursuit of Abner (2 Sam. 2:24). It lay to the east of Gibeon.

According to the Book of Mormon, Ammah was a Nephite missionary that lived in the 1st century BC. He was a companion to the missionary Aaron, who was the brother of the great missionary Ammon. Along with the brothers of Ammon, Ammah was part of the missionary delegation to the Lamanites that eventually led to the conversion of the Ammonites. He is mentioned briefly in chapters 20 and 21 of the Book of Alma, and it is evident that he spent time in prison along with Aaron during his ministry.