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...核燃料生产出来后被装在金属罐中。These weapons also had a heavy brass guard which encased almost the whole hand...这些武器还有一个沉重的黄铜护手，几乎把整个手都包住了。