|Easton's Bible Dictionary|
Height, a town of Moab, or simply, the height=the citadel, some fortress so called; or perhaps a general name for the highlands of Moab, as some think (Jeremiah 48:1). In Isaiah 25:12, the word is rendered "high fort."
Int. Standard Bible Encyclopedia
mis'-gab (ha-misgabh; Codex Vaticanus Amath; Codex Alexandrinus to krataioma): Named with Nebo and Kiriathaim in the denunciation of doom against Moab (Jeremiah 48:1). No trace of any name resembling this has been found. Possibly we should take it, not as a place-name, but as an appellation of some strong fortress, perhaps of Kir-moab itself. The term is elsewhere translated "high fortress" (Isaiah 25:12, etc.).
Misgab (1 Occurrence)
Jeremiah 48:1 Of Moab. Thus says Yahweh of Armies, the God of Israel: Woe to Nebo! for it is laid waste; Kiriathaim is disappointed, it is taken; Misgab is put to shame and broken down. (WEB KJV JPS ASV DBY WBS)