caisson
/kəˈsuːn/noun
1
- a large watertight chamber, open at the bottom, from which the water is kept out by air pressure and in which construction work may be carried out under water沉箱（底部开口, 因有气压而使水无法进入, 从而可进行施工的大型防水室）。
1.1
- a floating vessel or watertight structure used as a gate across the entrance of a dry dock or basin浮箱式坞门。
2
- historical a chest or wagon for holding or conveying ammunition〈史〉弹药箱; 弹药运输箱。
词源
late 17th cent.: from French, literally 'large chest', from Italian cassone, the spelling having been altered in French by association with caisse 'case'.