1N-COUNT (大楼的)蓄水箱,水塔;(抽水马桶的)水箱 A cistern is a container which stores the water supply for a building, or that holds the water for flushing a toilet. (大楼的)蓄水箱,水塔;(抽水马桶的)水箱 [mainly British]
in AM, usually use 美国英语通常用 tank
2N-COUNT (贮存雨水的)地下蓄水罐 A cistern is a container for storing rain water. (贮存雨水的)地下蓄水罐 [mainly US]