Ngong is a corrupted name. The Maasai use to call the place arround the hills Engongu Emuny(the Well or the Eye of the rhino). Engongu in maasai language is the eye,but it is also a water spring. Since most non maasai were not able to pronounce Engongu Emuny they corrupted the name to it's present name Ngong.

-courtesy of Moses Litei