- Historical a strong wooden fort with a projecting second story and openings in the walls for the defenders to shoot from
- ☆ any building of squared timber or logs
- ☆ Mil. a small defensive structure of concrete
- ☆ a dome-shaped, heavily reinforced structure, with periscopes and detecting instruments, to protect observers of missile launchings, nuclear explosions, etc.
- A military fortification constructed of sturdy material, such as concrete, and designed with ports for defensive firing or observation.
- A heavily reinforced building used for launch operations of missiles and space launch vehicles.
- A fort made of squared timbers with a projecting upper story.