If a person or an object is encased in something, they are completely covered or surrounded by it.
例句
When nuclear fuel is manufactured it is encased in metal cans...核燃料生產出來后被裝在金屬罐中。These weapons also had a heavy brass guard which encased almost the whole hand...這些武器還有一個沉重的黃銅護手，幾乎把整個手都包住了。