Fortification . a defensive barrier consisting of strong posts or timbers fixed upright in the ground.

an enclosure or pen made with posts and stakes.

U.S. Military . a prison for military personnel.

to protect, fortify, or encompass with a stockade.

noun

barrier , cage , camp , can * , cell , clink * , cooler * , coop , corral , detention camp , dungeon , fence , jailhouse , joint * , pen , penal institution , penitentiary , pound , prison , protection , slammer * , sty , can , cooler , enclosure , jail , kennel