a fortified great house: the citadel or palace of a king or the powerful, at once a grand residence and a defensible stronghold
This word names the largest and strongest building of an ancient town: the great house of a king or of the ruling families, built high and heavily to be both a residence and a fortress. It is not a neutral word for any home. It pictures the fortified heart of a city, the place where power lived and where a population made its last stand.
Because the building was both a luxury dwelling and a defensive stronghold, no single English word covers it. Translators rotate among palace, citadel, stronghold, fortress, and castle depending on which side of the picture a verse presses. In one passage it is where a king is killed in his own throne rooms, in another it is the high refuge that keeps a city safe.
The word lives mostly in the prophets, and above all in Amos, who repeats it like a drumbeat: fire will devour the fortified palaces of Damascus, Gaza, Tyre, Edom, Ammon, Moab, Judah, and Israel alike. There these buildings stand for arrogant, oppressive wealth and for the false security of the powerful. On the other side, the songs of Zion point to Jerusalem's citadels as a genuine refuge, because God himself is the strength inside them.