'Strongholds' in the Bible

David stayed in the wilderness in the strongholds, and remained in the hill country in the wilderness of Ziph. And Saul sought him every day, but God did not deliver him into his hand.

Then Ziphites came up to Saul at Gibeah, saying, “Is David not hiding with us in the strongholds at Horesh, on the hill of Hachilah, which is on the south of Jeshimon?

David went up from there and stayed in the strongholds of Engedi.