Presumable, this hill is located somewhere in the vicinity of Antionum.
It is not clear whether the Nephites ever retook Antionum, and if they didn't, it seems possible that the Hill Onidah could be the same as the Place of Onidah.
"On" in Hebrew signifies the concepts of vigor, virility, and wealth. Nun-dalet-heh and nun-dalet-chet are separate roots that signify similar ideas, a separation. So, we have the idea of a type of poverty implied, but also a lack of social power. Poor and cast out. Nun-dalet-heh conveys a ceremonial our social separation. This could be social ostracization, or separation to promote cleanliness. Nun-dalet-chet, on the other hand conveys the idea of being either banished or seduced away.