retention
/rɪˈtenʃən/noun
mass noun
1- the continued possession, use, or control of something保留, 保持：
the retention of direct control by central government.
中央政府直接控制权的保留。
1.1
- the fact of keeping something in one's memory记忆：
the children's retention of facts.
孩子们对事实的记忆。
1.2
- the action of absorbing and continuing to hold a substance（对物质的）吸收和保持：
the soil's retention of moisture.
土壤对水分的吸收和保持。
1.3
- failure to eliminate a substance from the body潴留; 停滞：
eating too much salt can lead to fluid retention.
吃盐太多可能会导致液潴留。
词源
late Middle English (denoting the power to retain something)： from Old French, from Latin retentio（n-）, from retinere 'hold back' （see RETAIN）.