'Stronghold' in the Bible

And the inhabitants of Jebus said to David, Thou shalt not come in hither. But David took the stronghold of Zion, which is the city of David.

And David dwelt in the stronghold; therefore they called it the city of David.

And David was then in the stronghold; and the Philistines' garrison was then at Bethlehem.

And of the Gadites, there separated themselves to David in the stronghold in the wilderness mighty men of valour, men fit for the service of war, armed with shield and spear; whose faces were like the faces of lions, and who were swift as the gazelles upon the mountains:

And there came of the children of Benjamin and Judah to the stronghold to David.