cistern
/ˈsɪstən/noun
1- a tank for storing water, especially one supplying taps or as part of a flushing toilet蓄水池, 蓄水箱（尤指装上龙头或阀门的水箱或抽水马桶的水箱）。
1.1
- an underground reservoir for rainwater地下雨水蓄水池。
词源
Middle English: from Old French cisterne, from Latin cisterna, from cista 'box' （see CIST2 ）.